Active vibration suppression apparatus, control method therefor, and exposure apparatus having active vibration suppression apparatus

ABSTRACT

An active vibration suppression apparatus includes an actuator fixed to a vibration suppression target, an inertial load driven relative to the target by the actuator, and a driving system which drives the actuator based on a first signal corresponding to the vibration, generated or to be generated, of the target. The driving system includes a compensation unit which performs a compensation for the first signal. The compensation, separately or as a composite compensation includes (i) a linear compensation for the first signal to obtain a first compensated signal, and (ii) a nonlinear compensation for the first compensated signal to obtain a second compensated signal. A rate of a change in the second compensated signal to a change in an absolute value of the first compensated signal becoming less with an increase of the absolute value.

FIELD OF THE INVENTION

The present invention relates to an active vibration suppression methodand apparatus which are suited to realizing the excellent performance ofan apparatus by stably and quickly suppressing vibrations such asrigid-body vibrations and structural resonance produced in a structureforming a semiconductor exposure apparatus, an exposure apparatus usingthe same, and the like.

BACKGROUND OF THE INVENTION

With an increase in the precision of a semiconductor exposure apparatus,a vibration isolation/suppression apparatus with higher performance hasbeen required. In a semiconductor exposure apparatus, in particular, itis required to prevent vibrations that affect exposure from beingproduced in an exposure stage or a structure forming an exposureapparatus body. For this purpose, the exposure apparatus body must beinsulated from external vibrations, including vibrations from anapparatus mount pedestal such as a floor, as much as possible, andvibrations produced when equipment, having a driving means such as anX-Y stage mounted on the apparatus main body, operates, must be quicklyreduced.

If structural resonance vibrations are produced in apparatus/equipmentmounted on the exposure apparatus body, and a sufficient dampingproperty is not ensured, these resonance vibrations must also beeffectively reduced/suppressed to prevent them from affecting theapparatus performance.

In the semiconductor exposure apparatus, in particular, theintermittent, repetitive operation, called step-and-repeat, of theexposure stage apparatus or scanning operation for scanning exposureexcites vibrations, in the apparatus body. The drive reaction forcegenerated by the stage apparatus and the load movement of the stageapparatus excite vibrations in equipment or a structure that forms theapparatus body. For a vibration isolation/suppression apparatus in thisfield, therefore, it is essentially required to insulate the apparatusbody from external vibrations including vibrations from an apparatusmount pedestal such as a floor, and to effectively reduce/suppressrigid-body vibrations and resonance vibrations produced in the apparatusbody when the equipment mounted on the apparatus body operates. In ascan exposure apparatus, in particular, since exposure is performedwhile an exposure stage apparatus performs a scanning operation, severerequirements are imposed on vibration reduction/suppression performance.Therefore, a vibration isolation/suppression apparatus with higherperformance becomes indispensable.

To satisfy such a requirement, various types of active vibrationisolation/suppression apparatuses have been developed and put intopractice, which detect the vibrations of a vibration isolation base onwhich a semiconductor exposure apparatus is mounted by using a sensor,to compensate for the resultant detection signal for the vibrations, andto feed back the resultant signal to each actuator for applying acontrol force to the vibration isolation base, thereby activelysuppressing vibration.

As a conventional vibration isolation/suppression apparatus for asemiconductor exposure apparatus, an active vibration isolationapparatus based on the vibration isolation leg scheme forreducing/suppressing the vibrations of the vibration isolation base byusing a support mechanism for vibration-suppressing/supporting thevibration isolation base has been widely used. More specifically, avibration isolation apparatus has been widely used, which controls thevibrations of the vibration isolation base by using actuators formed byair springs for supporting the vibration isolation base on an apparatusmount pedestal or a combination of such air springs and electromagneticactuators that are placed dynamically parallel to the air springs toapply a control force between the vibration isolation base and theapparatus mount pedestal.

An active vibration isolation apparatus of this type and a semiconductorexposure apparatus using this vibration isolation apparatus aredisclosed in “Vibration Isolation Apparatus, Exposure Apparatus andDevice Manufacturing Method using the Same, and Vibration IsolationMethod”, Japanese Patent Laid-Open No. 11-294520 proposed by the presentapplicant. According to this prior art, an active vibration isolationapparatus configured to reduce/suppress the vibrations of a vibrationisolation base is disclosed, which uses air springs, as air actuators,which support the vibration isolation base on an apparatus mountpedestal, and also uses electromagnetic linear motors for applying acontrol force between the vibration isolation base and the apparatusmount pedestal. In this apparatus, each actuator is controlled on thebasis of a signal obtained by detecting any displacement, acceleration,or the like, of the vibration isolation base using a sensor andperforming a compensation computation for the signal, such as a signalbeing obtained by compensating for a signal from equipment having adriving means such as an X-Y stage mounted on the vibration isolationbase, a signal being obtained by detecting the vibrations of theapparatus mount pedestal and performing a compensation computation forthe resultant signal, or the like. This apparatus realizes excellentvibration isolation/suppression performance, which the active vibrationisolation apparatus based on the pneumatic driving scheme widely used inthe past does not have, by respectively allocating control functions toair actuators capable of easily obtaining a large thrust andelectromagnetic actuators with excellent response properties inconsideration of the merits of the two types of actuators.

An active vibration suppression apparatus, called an active mass damperor a countermass, tends to be used in the field of precision vibrationcontrol as well, which is designed to perform vibration control morefinely than such an active vibration isolation apparatus based on thevibration isolation leg scheme and to realize more sophisticatedvibration isolation/suppression control by driving an inertial loadserving as a weight by using an actuator and using the resultant drivereaction force as a control force.

Such conventional active vibration suppression apparatuses are disclosedin “Active Vibration Suppression Apparatus and Semiconductor ExposureApparatus Using the Same”, Japanese Patent Application No. 11-151141filed by the present applicant, “Stage Apparatus, Exposure Apparatususing the Same, and Device Manufacturing Method”, Japanese PatentLaid-Open No. 11-190786, “Active Vibration Suppression Apparatus”,Japanese Patent Application No. 2000-122731 filed by the presentapplicant, and the like. Methods and apparatuses forreducing/suppressing vibrations are also disclosed in these references.

FIG. 17 is a perspective view for explaining the structure of avibration suppression apparatus proposed as “Active VibrationSuppression Apparatus and Semiconductor Exposure Apparatus Using theSame”, Japanese Patent Application No. 11-151141. This vibrationsuppression apparatus is configured to drive a mass serving as a weightin the straight direction by using an actuator for generating a thrustin the straight direction. The apparatus shown in FIG. 17 suppressesvibrations in the vertical direction.

This apparatus is comprised of a linear-acting actuator 81 such as anelectromagnetic linear motor and an inertial load 82 driven by thelinear-acting actuator 81 in the straight direction. FIG. 17 shows anexample of the apparatus using an electromagnetic linear motor as alinear-acting actuator, which generates a thrust in the straightdirection indicated by the arrow in FIG. 17 by the interaction between astator 81 a having a coil winding and a movable part 81 b fixed to theinertial load 82 and having a permanent magnet. The linear-actingactuator 81 is fastened to a vibration suppression target through a basemember 83 and generates a thrust to displace the inertial load 82 withrespect to the vibration suppression target. When the linear-actingactuator 81 is caused to generate a thrust to displace the inertial load82, the reaction force of the thrust acting on the inertial load 82 actson the vibration suppression target.

FIG. 18 shows an example of the structure of a vibration suppressionapparatus that acts to reduce vibrations in the horizontal direction bya similar method. Like the apparatus shown in FIG. 17, this apparatus iscomprised of a linear-acting actuator 84 such as an electromagneticlinear motor, an inertial load 85 driven in the straight direction bythe linear-acting actuator 84, and the like. FIG. 18 shows an example ofthe apparatus using an electromagnetic linear motor as a linear-actingactuator, which generates a thrust in the straight direction indicatedby the arrow in FIG. 18 by the interaction between a stator 84 a havinga coil winding and a movable part 84 b fixed to the inertial load 85 andhaving a permanent magnet. The linear-acting actuator 84 is fastened toa vibration suppression target through a base member 86 and generates athrust to displace the inertial load 85 with respect to the vibrationsuppression target. When the linear-acting actuator 84 is caused togenerate a thrust to displace the inertial load 85, the reaction forceof a thrust acting on the inertial load 85 acts on the vibrationsuppression target.

An active vibration suppression apparatus of this type uses such areaction force as a control force for a vibration suppression target,and adjusts the control force on the basis of a signal obtained bycompensating for a detection signal representing the vibrations of thevibration suppression target, thereby performing vibration control. Thatis, unlike an active vibration isolation apparatus based on thevibration isolation leg scheme, this apparatus can reduce the vibrationsof a vibration isolation base or equipment without applying anyunnecessary force as the reaction force of a control force for vibrationcontrol to a portion outside the apparatus. This apparatus, therefore,has the merit of preventing the reaction force of a force for thereduction/suppression of vibrations from exciting vibrations in anapparatus mount pedestal or peripheral environment, which causevibrations affecting precision equipment mounted on the vibrationisolation base.

An apparatus of this type is configured to obtain a force acting on avibration suppression target from a drive reaction force of an inertialload in a vibration suppression unit instead of being generated betweenexternal equipment and a vibration suppression target. If, therefore,the vibration suppression apparatus can be manufactured into anappropriate shape, a vibration suppressing effect can be obtained bylocating the apparatus to a place where a dashpot used to reduce thestructural resonance vibrations of equipment or a reinforcing member forensuring rigidity cannot be installed.

In actually using an active vibration suppression apparatus of this typefor applying a control force to a vibration suppression target by usinga linear-acting actuator, an inertial load and its movable stroke mustbe appropriately designed in consideration of a control force necessaryfor the reduction of vibrations, the frequency band of vibrations to besuppressed, and the like.

Assume that the vibrations of a vibration suppression target whichoriginate from the drive reaction force produced by equipment such as anX-Y stage are reduced by using an active vibration suppression apparatusof the type described above with reference to FIGS. 17 and 18. In thiscase, to obtain a control force required to suppress vibrations, anapparatus having an inertial load mass and a movable stroke equal to orsimilar to those of the X-Y stage must be used. However, since anallowable space is limited, a mass and movable stroke sufficient toobtain a predetermined vibration suppressing action and effect may notbe ensured.

Assume that vibrations to be suppressed by an active vibrationsuppression apparatus of this type are the resonance vibrations of astructure having a relatively high resonance frequency, and a large massor stroke are not required to suppress the vibrations of the structureitself. Even in this case, if equipment such as an X-Y stage operates ona surface plate, or the like, rigidly fastened to a vibrationsuppression target, a vibration isolation base on which the X-Y stage,and the like, are mounted vibrates at a low frequency corresponding tothe natural frequency of a vibration system constituted by support legsof the vibration isolation base. As a consequence, the structure as thevibration suppression target also vibrates at the low frequency. In sucha case, due to the influence of the low-frequency vibrations produced inthe vibration isolation base and the structure as the vibrationsuppression target, the inertial load as a part of the active vibrationsuppression apparatus may greatly swing and operate beyond its movablestroke.

If the stroke of the inertial load is limited due to such restrictionson the specifications of the structure of the vibration suppressionapparatus, the generation of vibrations of frequency components otherthan the control target, or the like, may prevent a sufficient vibrationsuppressing effect from being obtained. Furthermore, the inertial loadmay collide with a member such as a stopper, which is placed to preventthe inertial load from exceeding the stroke range. This may create alarge shock to the vibration suppression control system, resulting in acontrol operation failure. In contrast to this, if the control gain issuppressed to prevent an inconvenience caused by stroke over, anecessary control effect cannot be ensured.

Under these circumstances, an active vibration isolation apparatus basedon the vibration isolation leg scheme that has been widely used in asemiconductor exposure apparatus, and the like, is configured to apply acontrol force to a vibration isolation base or a member rigidly fastenedto the base. That is, the apparatus is configured to reduce/suppress thevibrations of the vibration isolation base or surface plate on whichvarious types of equipment constituting an exposure apparatus aremounted. In this case, if equipment and structures are rigidly fastenedto the vibration isolation base or surface plate, and no structuralresonance occurs, the vibrations of the mounted equipment and structurescan be satisfactorily reduced/suppressed by the vibration isolationapparatus based on the vibration isolation leg scheme.

In many cases, in an actual apparatus, however, structural resonancevibrations are produced in mounted equipment and structures due tovarious restrictions on equipment design, and a satisfactory dampingproperty cannot be provided for the resonance vibrations. In addition,when heavy equipment and structures are fastened to the vibrationisolation base or surface plate, a spring/mass system may be formed dueto insufficient fastening rigidity, and vibrations may be produced at alevel that cannot be neglected in ensuring satisfactory apparatusperformance.

When such vibrations are produced in a mounted equipment and structures,even if the vibrations of the vibration isolation base or surface plateare reduced/suppressed, those of these equipment and structures cannotbe sufficiently suppressed. This affects the precision of the apparatusand degrades the exposure performance. In a semiconductor exposureapparatus, in particular, some structure needs to have a cantileversupport structure in terms of equipment layout design, and swingingvibrations are produced around the fulcrum of the structure, affectingthe performance of the semiconductor exposure apparatus.

The vibrations of mounted equipment/structure of this type can bereduced/suppressed by interposing a dashpot for providing a dampingproperty between the external equipment and the vibration suppressiontarget or by attaching a reinforcing member for ensuring rigidity.However, such a member cannot be attached because of restrictions on theequipment layout design in many cases. For this reason, vibrations suchas structural resonance of equipment/structure cannot be sufficientlysuppressed, and such vibrations often become big factors that hinder animprovement in the performance of a semiconductor exposure apparatus.Therefore, demands have arisen for a means/method of effectivelyreducing/suppressing (i) rigid-body vibrations and structural resonanceof equipment/structures having severe restrictions on the layout design,and for a semiconductor exposure apparatus having the means/method.

In addition, with an increase in the precision of a semiconductorexposure apparatus, it is required to further reduce the influence ofenvironmental vibrations of an apparatus mount pedestal, and the like.In order to meet such a requirement, a control method has been proposedand applied to the above active vibration isolation apparatus based onthe vibration isolation leg scheme, which compensates for a detectionsignal representing the vibrations of an apparatus mount pedestal forthese vibrations and feeding forward the resultant signal to an actuatorfor applying a control force to a vibration isolation base. According tothis method, the actuator is made to generate a control force to cancelout vibrations transmitted from the apparatus mount pedestal to thevibration isolation base through vibration isolation legs on the basisof a detection signal representing the vibrations of the apparatus mountpedestal. This method can reduce/suppress the amount of vibrationstransmitted from the apparatus mount pedestal much more than the controlscheme using only a detection signal representing the vibrations of thevibration isolation base.

This control operation is, however, performed by using a detectionsignal representing the vibrations of a floor or apparatus mountpedestal, i.e., a detection signal representing a physical quantityincluding many uncertainties in terms of the generation mechanism ofvibrations. For this reason, owing to various uncertainties acting in anapparatus mount environment, unpredictable, uncertain signals may be fedforward to the control system. That is, this control method has a weakpoint in the reliability of vibration control operation.

Such a problem can be effectively solved by a method of reducingvibrations transmitted to the exposure apparatus body by suppressing thevibrations of a structure itself on the apparatus pedestal on which thesemiconductor exposure apparatus is installed. In consideration of sucha point as well, demands have arisen for a means/method ofreducing/suppressing vibrations of types that are not suited to avibration isolation apparatus based on the vibration isolation legscheme.

In the prior art associated with Japanese Patent Application No.11-151141, and the like, there is no detailed description about avibration suppression method and an apparatus aimed at removing thevibrations of a structure as a part of a semiconductor exposureapparatus, more specifically, the vibrations of a cantilever supportstructure as a part of a semiconductor exposure apparatus, a structureon the mount pedestal side on which vibration isolation legs forvibration-isolating/supporting a semiconductor exposure apparatus aremounted, and the like, as in the apparatus according to the presentinvention. In “Active Vibration Suppression Apparatus”, Japanese PatentApplication No. 2000-122731, and Japanese Patent Laid-Open No.11-190786, a vibration suppression apparatus for a semiconductorexposure apparatus is described. Basically, however, such references arelimited to the disclosure of vibration suppression methods andapparatuses aimed at suppressing rigid-body vibrations such as thevibrations of a vibration isolation base or surface plate as a part ofan exposure apparatus body.

SUMMARY OF THE INVENTION

The present invention has been proposed to solve the conventionalproblems.

It is the first object of the present invention to provide an activevibration suppression apparatus and a control method therefor, whichsolve the above problems caused when severe restrictions are imposed onthe movable stroke, mass, and the like, of an inertial load in an activevibration suppression apparatus using an actuator, can realize both avibration suppressing effect and stable operation upon production oflarge vibrations, and can obtain maximum vibration suppressionperformance under the restrictions.

It is the second object of the present invention to provide an activevibration suppression apparatus which can stably and quickly suppressvibrations of the types that cannot be sufficiently reduced/suppressedby a conventional vibration isolation apparatus based on the vibrationisolation leg scheme or vibrations of the types that are not suited tothe application of the vibration isolation apparatus based on thevibration isolation leg scheme and has a structure in which therestrictions on the equipment layout design are not severe, and ahigh-performance exposure apparatus using the active vibrationsuppression apparatus.

More specifically, it is the third object of the present invention toeffectively reduce/suppress vibrations of the types that fall outsidethe application range of conventional techniques, e.g., local vibrationssuch as structural resonance caused in a cantilever support structure asa part of an exposure apparatus or structural vibrations that are notproduced in an exposure apparatus body, but are produced in a structureon the mount pedestal on which the apparatus is mounted, as well asrigid-body vibrations caused in a structure as a part of a main bodystructure such as a semiconductor exposure apparatus.

In order to achieve the above objects, according to the presentinvention, the following apparatuses, and the like, are described indetail below.

An active vibration suppression apparatus according to the presentinvention comprises: an actuator which is fixed to a vibrationsuppression target and generates a thrust; an inertial load which isconnected to the actuator and is driven relative to the vibrationsuppression target in accordance with the thrust generated by theactuator; and a driving circuit for generating a driving command signalfor controlling driving of the inertial load and driving the actuator inaccordance with the driving command signal, wherein the actuator drivesthe inertial load with the generated thrust, and applies a drivereaction force generated upon driving of the inertial load as a controlforce to the vibration suppression target, thereby reducing vibrationsproduced in the vibration suppression target.

Preferably, in the above active vibration suppression apparatus, theactuator generates a thrust in a straight direction to drive theinertial load in the straight direction, and reduces vibrations of thevibration suppression target in the straight direction with a drivereaction force in the straight direction.

Note that a vibration suppression unit of the type that applies acontrol force to a vibration suppression target by driving an inertialload in the straight direction will be referred to as a linear-actingvibration suppression unit hereinafter.

Preferably, the above active vibration suppression apparatus furthercomprises: a vibration detection unit for detecting vibrations of thevibration suppression target; and a compensation computation section forperforming compensation computation processing for a signalcorresponding to the vibrations of the vibration suppression targetwhich are detected by the vibration detection unit.

In this case, preferably, in the above active vibration suppressionapparatus, the compensation computation section performs a nonlinearcompensation computation for the signal corresponding to the vibrationsof the vibration suppression target which are detected by the vibrationdetection unit.

Preferably, in the above active vibration suppression apparatus, thedriving circuit generates a driving command signal for driving theactuator on the basis of a signal obtained by the compensationcomputation section, and the actuator generates a control force forreducing the vibrations of the vibration suppression target by drivingthe inertial load on the basis of the driving command signal.

Preferably, in the above active vibration suppression apparatus, thecompensation computation section performs a linear compensationcomputation including at least one of proportional compensation,integral compensation, differential compensation, phase-leadcompensation, and phase-lag compensation for a signal corresponding tothe vibrations of the vibration suppression target which are detected bythe vibration detection unit, and further performs a nonlinearcompensation computation for a signal having undergone the linearcompensation computation.

Preferably, in the above active vibration suppression apparatus, thenonlinear compensation computation is described by a nonlinear functionwhich is a monotonously increasing or decreasing function and outputs asignal obtained by multiplying an input signal by a gain whose absolutevalue decreases as a value of the input signal separates from a neutralpoint of the input signal.

Preferably, in the above active vibration suppression apparatus, whenequipment having driving means is mounted on the vibration suppressiontarget, or the equipment having the driving means is fastened to thevibration suppression target with high rigidity, and the driving meansof the equipment vibrates the vibration suppression target, theapparatus further comprises a feedforward compensation computationsection for receiving one of a signal obtained by measuring operation ofthe equipment having the driving means and a control signal from acontrol section for the equipment and performing feedforwardcompensation computation processing for the signal, the driving circuitgenerates a driving command signal for driving the actuator on the basisof an output signal from the feedforward compensation computationsection, and the actuator drives the inertial load on the basis of thedriving command signal, thereby generating a control force for reducingthe vibrations of the vibration suppression target.

In this case, preferably, in the above vibration suppression apparatus,the feedforward compensation computation section performs a nonlinearcompensation computation for one of the signal obtained by measuring theoperation state of the equipment having the driving means and thecontrol signal from the control section for the equipment.

Preferably, in the above active vibration suppression apparatus, thefeedforward compensation computation section performs a linearcompensation including at least one of proportional compensation,integral compensation, differential compensation, phase-leadcompensation, and phase-lag compensation for the signal obtained bymeasuring the operation state of the equipment having the driving meansand the control signal from the control section for the equipment, andfurther performs a nonlinear compensation for a signal having undergonethe linear compensation computation.

Preferably, in the above active vibration suppression apparatus, thenonlinear compensation computation is described by a nonlinear functionwhich is a monotonously increasing or decreasing function and outputs asignal obtained by multiplying an input signal by a gain whose absolutevalue decreases as a value of the input signal separates from a neutralpoint of the input signal.

In addition, according to the present invention, there is provided acontrol method for an active vibration suppression apparatus comprising:the detection step of detecting a signal corresponding to vibrations ofa vibration suppression target by using a vibration detection unit; theacquisition step of performing processing to acquire an operation signalobtained by measuring an operation state of equipment having drivingmeans and/or a control signal from the equipment; the first computationstep of performing a first nonlinear compensation computation for thesignal detected in the detection step; the second computation step ofperforming a second nonlinear compensation computation for the signalacquired in the acquisition step; and the control step of driving anactuator and generating a control force for reducing the vibrations ofthe vibration suppression target on the basis of the signal havingundergone the nonlinear compensation computation in the first and/orsecond computation step.

Furthermore, an active vibration suppression apparatus according to thepresent invention comprises: a rotating actuator which is fixed to avibration suppression target and generates a torque in a rotationaldirection; an inertial load which is connected to the actuator and movesin the rotational direction relative to the vibration suppression targetin accordance with a torque of the actuator; and a driving circuit forgenerating a driving command signal for controlling the inertial loadand driving the rotating actuator in accordance with the driving commandsignal, wherein the rotating actuator rotates/drives the inertial loadwith a generated torque, and reduces vibrations produced in thevibration suppression target by applying a drive reaction forcegenerated upon rotating/driving the inertial load as a control torque tothe vibration suppression target.

Preferably, the above active vibration suppression apparatus furthercomprises: a rotational vibration detection unit for detectingvibrations of the vibration suppression target in a rotational motiondirection; and a rotational vibration compensation computation sectionfor performing compensation computation processing for a signalcorresponding to the rotational vibrations of the vibration suppressiontarget which are detected by the rotational vibration detection unit.

Preferably, in the above active vibration suppression apparatus, thedriving circuit generates a driving command signal for driving therotating actuator on the basis of the signal obtained by the rotationalvibration compensation computation section, and the rotating actuatorrotates/drives the inertial load on the basis of the driving commandsignal, thereby generating a control torque for reducing the vibrationsof the vibration suppression target.

Preferably, in the above active vibration suppression apparatus, whenequipment having driving means is mounted on the vibration suppressiontarget, or the equipment having the driving means is fastened to thevibration suppression target with high rigidity, and the driving meansof the equipment vibrates the vibration suppression target, theapparatus further comprises a second feedforward compensationcomputation section for receiving one of a signal obtained by measuringoperation of the equipment having the driving means and a control signalfrom a control section for the equipment and performing feedforwardcompensation computation processing for the signal, the driving circuitgenerates a driving command signal for driving the actuator on the basisof an output signal from the second feedforward compensation computationsection, and the actuator drives the inertial load on the basis of thedriving command signal, thereby generating a control torque for reducingthe vibrations of the vibration suppression target.

Preferably, the above active vibration suppression apparatus comprisesrigidity providing means functioning to restore the inertial load to apredetermined a neutral position.

According to the present invention, there is provided a control methodfor an active vibration suppression apparatus comprising: the detectionstep of detecting a signal corresponding to vibrations of a vibrationsuppression target in a rotational direction by using a vibrationdetection unit; the acquisition step of performing processing to acquirean operation signal obtained by measuring an operation state ofequipment having driving means and/or a control signal from theequipment; the first computation step of performing a first nonlinearcompensation computation for the signal detected in the detection step;the second computation step of performing a second nonlinearcompensation computation for the signal acquired in the acquisitionstep; and the control step of driving an actuator and generating acontrol torque for reducing the vibrations of the vibration suppressiontarget on the basis of the signal having undergone the nonlinearcompensation computation in the first and/or second computation step.

An exposure apparatus according to the present invention comprises: astage apparatus having a substrate or master plate as an exposure targetmounted thereon and performing precision positioning operation; and anactive vibration suppression apparatus which acts on a surface plate onwhich the stage apparatus is mounted or an exposure apparatus housingstructure mounted on the surface plate to reduce vibrations in thesurface plate or the exposure apparatus housing structure in atranslation direction which are produced upon driving of the stageapparatus, the active vibration suppression apparatus including anactuator which is fixed to the surface plate or an exposure apparatushousing structure and generates a thrust, an inertial load which isconnected to the actuator and is driven relative to the surface plate orexposure apparatus housing structure in accordance with the thrustgenerated by the actuator, and a driving circuit for generating adriving command signal for controlling driving of the inertial load anddriving the actuator in accordance with the driving command signal,wherein the actuator drives the inertial load with the generated thrust,and applies a drive reaction force generated upon driving of theinertial load as a control force to the surface plate or exposureapparatus housing structure to reduce vibrations produced in the surfaceplate or the exposure apparatus housing structure.

An exposure apparatus according to the present invention comprises: astage apparatus having a substrate or master plate as an exposure targetmounted thereon and performing a precision positioning operation; and anactive vibration suppression apparatus which acts on a surface plate onwhich the stage apparatus is mounted or an exposure apparatus housingstructure mounted on the surface plate to reduce vibrations of thesurface plate or exposure apparatus housing structure in a rotationaldirection which are produced upon driving of the stage apparatus, theactive vibration suppression apparatus including a rotating actuatorwhich is fixed to the surface plate or exposure apparatus housingstructure and generates a torque in a rotational direction, an inertialload which is connected to the actuator and moves in the rotationaldirection relative to the surface plate or exposure apparatus housingstructure in accordance with a torque of the actuator, and a drivingcircuit for generating a driving command signal for controlling theinertial load and driving the rotating actuator in accordance with thedriving command signal, wherein the rotating actuator rotates/drives theinertial load with a generated torque, and reduces vibrations producedin the surface plate or the exposure apparatus housing structure byapplying a drive reaction force generated upon rotating/driving theinertial load as a control torque to the surface plate or exposureapparatus housing structure.

An exposure apparatus according to the present invention comprises: astage apparatus having a substrate or master plate as an exposure targetmounted thereon and performing precision positioning operation; a firstactive vibration suppression apparatus which acts on a surface plate onwhich the stage apparatus is mounted or an exposure apparatus housingstructure mounted on the surface plate to reduce vibrations of thesurface plate or the exposure apparatus housing structure in atranslation direction which are produced upon driving of the stageapparatus; and a second active vibration suppression apparatus forreducing rotational vibrations of the surface plate or the exposureapparatus housing structure, wherein vibrations produced upon driving ofthe stage apparatus are reduced by the first active vibrationsuppression apparatus and/or the second active vibration suppressionapparatus.

Preferably, in the above exposure apparatus, the first active vibrationsuppression apparatus comprises: an actuator which is fixed to thesurface plate or the exposure apparatus housing structure and generatesa thrust, an inertial load which is connected to the actuator and isdriven relative to the surface plate or the exposure apparatus housingstructure in accordance with the thrust generated by the actuator, and adriving circuit for generating a driving command signal for controllingdriving of the inertial load and driving the actuator in accordance withthe driving command signal, wherein the actuator drives the inertialload with the generated thrust, and applies a drive reaction forcegenerated upon driving of the inertial load as a control force to thesurface plate or the exposure apparatus housing structure to reducevibrations produced in the surface plate or the exposure apparatushousing structure.

Preferably, in the above exposure apparatus, the second active vibrationsuppression apparatus comprises: a rotating actuator which is fixed tothe surface plate or the exposure apparatus housing structure andgenerates a torque in a rotational direction, an inertial load which isconnected to the actuator and moves in the rotational direction relativeto the surface plate or the exposure apparatus housing structure inaccordance with a torque of the actuator, and a driving circuit forgenerating a driving command signal for controlling the inertial loadand driving the rotating actuator in accordance with the driving commandsignal, wherein the rotating actuator rotates/drives the inertial loadwith a generated torque, and reduces vibrations produced in the surfaceplate or the exposure apparatus housing structure by applying a drivereaction force generated upon rotating/driving the inertial load as acontrol torque to the surface plate or the exposure apparatus housingstructure.

An exposure apparatus according to the present invention comprises anactive vibration suppression apparatus which is mounted on a structuralmember of a cantilever support structure forming a housing structure ofthe exposure apparatus and generates a drive reaction force forreducing/suppressing structural vibrations produced around a cantileversupport portion of the structural member, wherein the active vibrationsuppression apparatus comprises: an actuator which is fixed to thestructural member of the cantilever support structure and generates athrust; an inertial load which is connected to the actuator and isdriven relative to the structural member of the cantilever supportstructure in accordance with the thrust generated by the actuator; and adriving circuit for generating a driving command signal for controllingdriving of the inertial load and driving the actuator in accordance withthe driving command signal, and wherein the actuator drives the inertialload with the generated thrust, and applies a drive reaction forcegenerated upon driving of the inertial load as a control force to thestructural member of the cantilever support structure to reducevibrations produced in the structural member of the cantilever supportstructure.

An exposure apparatus according to the present invention comprises anactive vibration suppression apparatus for reducing/suppressingrotational vibrations around a rotation center of a support portion of acantilever support structure forming a housing structure of the exposureapparatus with respect to a structural member of the cantilever supportstructure by acting in a tangential direction with respect to adirection of the rotational vibrations at a position as distant aspossible from the support portion, wherein the active vibrationsuppression apparatus comprises: an actuator which is fixed to thestructural member of the cantilever support structure and generates athrust; an inertial load which is connected to the actuator and isdriven relative to the structural member of the cantilever supportstructure in accordance with the thrust generated by the actuator; and adriving circuit for generating a driving command signal for controllingthe inertial load and driving the actuator in accordance with thedriving command signal, wherein the actuator drives the inertial loadwith a generated thrust, and reduces vibrations produced in thestructural member of the cantilever support structure by applying adrive reaction force generated upon driving the inertial load as acontrol thrust to the structural member of the cantilever supportstructure.

Preferably, an exposure apparatus comprises an active vibrationsuppression apparatus for reducing/suppressing rotational vibrationsaround a rotation center of a support portion of a cantilever supportstructure forming a housing structure of the exposure apparatus withrespect to a structural member of the cantilever support structure bygenerating a control torque in a direction of the rotational vibrationswith the support portion being a rotation center, wherein the activevibration suppression apparatus includes: an actuator which is fixed tothe structural member of the cantilever support structure and generatesa thrust in a rotational direction; an inertial load which is connectedto the actuator and is driven relative to the structural member of thecantilever support structure in accordance with the thrust generated bythe actuator; and a driving circuit for generating a driving commandsignal for controlling the inertial load and driving the actuator inaccordance with the driving command signal, and wherein the actuatordrives the inertial load with a generated thrust, and reduces vibrationsproduced in the structural member of the cantilever support structure byapplying a drive reaction force generated upon driving the inertial loadas a control thrust to the structural member of the cantilever supportstructure.

Preferably, in the above exposure apparatus, the cantilever supportstructure is a mechanical structure forming an illumination optical unitfor emitting exposure light for exposing a photosensitive substrate to acircuit pattern formed on a master plate through an optical lens.

An exposure apparatus according to the present invention comprises anactive vibration suppression apparatus which is installed on anapparatus mount pedestal side structure on which the exposure apparatusis installed and actively reduces vibrations transmitted from theapparatus mount pedestal side structure to the exposure apparatus,wherein the active vibration suppression apparatus includes: an actuatorwhich is fixed to an apparatus mount pedestal side structure andgenerates a thrust; an inertial load which is connected to the actuatorand is driven relative to the apparatus mount pedestal side structure inaccordance with the thrust generated by the actuator; and a drivingcircuit for generating a driving command signal for controlling drivingof the inertial load and driving the actuator in accordance with thedriving command signal, and wherein the actuator drives the inertialload with the generated thrust, and applies a drive reaction forcegenerated upon driving of the inertial load as a control force to theapparatus mount pedestal side structure, thereby reducing vibrationsproduced in the apparatus mount pedestal side structure.

A semiconductor device manufacturing method according to the presentinvention comprises: the step of installing a plurality of semiconductormanufacturing apparatuses including an exposure apparatus in asemiconductor manufacturing factory; and the step of manufacturing asemiconductor device by using the plurality of semiconductormanufacturing apparatuses, the exposure apparatus including a stageapparatus having a substrate or master plate as an exposure targetmounted thereon and performing precision positioning operation, and anactive vibration suppression apparatus which acts on a surface plate onwhich the stage apparatus is mounted or an exposure apparatus housingstructure mounted on the surface plate to reduce vibrations of thesurface plate or the exposure apparatus housing structure in atranslation direction which are produced upon driving of the stageapparatus, the active vibration suppression apparatus including anactuator which is fixed to the surface plate or the exposure apparatushousing structure and generates a thrust, an inertial load which isconnected to the actuator and is driven relative to the surface plate orthe exposure apparatus housing structure in accordance with the thrustgenerated by the actuator, and a driving circuit for generating adriving command signal for controlling driving of the inertial load anddriving the actuator in accordance with the driving command signal,wherein the actuator drives the inertial load with the generated thrust,and applies a drive reaction force generated upon driving of theinertial load as a control force to the surface plate or the exposureapparatus housing structure to reduce vibrations produced in the surfaceplate or the exposure apparatus housing structure.

A semiconductor device manufacturing method according to the presentinvention comprises: the step of installing a plurality of semiconductormanufacturing apparatuses including an exposure apparatus in asemiconductor manufacturing factory; and the step of manufacturing asemiconductor device by using the plurality of semiconductormanufacturing apparatuses, the exposure apparatus including a stageapparatus having a substrate or master plate as an exposure targetmounted thereon and performing precision positioning operation, and anactive vibration suppression apparatus which acts on a surface plate onwhich the stage apparatus is mounted or an exposure apparatus housingstructure mounted on the surface plate to reduce vibrations of thesurface plate or the exposure apparatus housing structure in arotational direction which are produced upon driving of the stageapparatus, the active vibration suppression apparatus including arotating actuator which is fixed to the surface plate or the exposureapparatus housing structure and generates a torque in a rotationaldirection, an inertial load which is connected to the actuator and movesin the rotational direction relative to the surface plate or theexposure apparatus housing structure in accordance with a torque of theactuator, and a driving circuit for generating a driving command signalfor controlling the inertial load and driving the rotating actuator inaccordance with the driving command signal, wherein the rotatingactuator rotates/drives the inertial load with a generated torque, andreduces vibrations produced in the surface plate or the exposureapparatus housing structure by applying a drive reaction force generatedupon rotating/driving the inertial load as a control torque to thesurface plate or the exposure apparatus housing structure.

Preferably, the above semiconductor device manufacturing method furthercomprises: the step of connecting the plurality of semiconductormanufacturing apparatuses via a local area network; the step ofconnecting the local area network to an external network outside thesemiconductor manufacturing factory; the step of acquiring informationassociated with the exposure apparatus from a database on the externalnetwork by using the local area network and the external network; andthe step of controlling the exposure apparatus on the basis of theacquired information.

Preferably, the above semiconductor device manufacturing method furthercomprises the step of accessing a database provided by a vendor or userof the exposure apparatus via the external network to obtain maintenanceinformation of the manufacturing apparatus by data communication, orperforming production management by data communication between thesemiconductor manufacturing factory and another semiconductormanufacturing factory via the external network.

A semiconductor manufacturing factory according to the present inventioncomprises: a plurality of semiconductor manufacturing apparatuses,including an exposure apparatus; a local area network for connecting themanufacturing apparatuses; and a gateway which connects the local areanetwork to an external network of the semiconductor manufacturingfactory and allows communication of information associated with at leastone of the plurality of semiconductor manufacturing apparatuses, theexposure apparatus including a stage apparatus having a substrate ormaster plate as an exposure target mounted thereon and performingprecision positioning operation, and an active vibration suppressionapparatus which acts on a surface plate on which the stage apparatus ismounted or on an exposure apparatus housing structure mounted on thesurface plate to reduce vibrations of the surface plate or the exposureapparatus housing structure in a translation direction, which areproduced upon driving of the stage apparatus, the active vibrationsuppression apparatus including an actuator which is fixed to thesurface plate or the exposure apparatus housing structure and generatesa thrust, an inertial load which is connected to the actuator and isdriven relative to the surface plate or the exposure apparatus housingstructure in accordance with the thrust generated by the actuator, and adriving circuit for generating a driving command signal for controllingdriving of the inertial load and driving the actuator in accordance withthe driving command signal, wherein the actuator drives the inertialload with the generated thrust, and applies a drive reaction forcegenerated upon driving of the inertial load as a control force to thesurface plate or the exposure apparatus housing structure to reducevibrations produced in the surface plate or the exposure apparatushousing structure.

A semiconductor manufacturing factory according to the present inventioncomprises: a plurality of semiconductor manufacturing apparatuses,including an exposure apparatus; a local area network for connecting themanufacturing apparatuses; and a gateway which connects the local areanetwork to an external network of the semiconductor manufacturingfactory and allows communication of information associated with at leastone of the plurality of semiconductor manufacturing apparatuses, theexposure apparatus including a stage apparatus having a substrate ormaster plate as an exposure target mounted thereon and performingprecision positioning operation; and an active vibration suppressionapparatus which acts on a surface plate on which the stage apparatus ismounted or an exposure apparatus housing structure mounted on thesurface plate to reduce vibrations of the surface plate or the exposureapparatus housing structure in a rotational direction which are producedupon driving of the stage apparatus, the active vibration suppressionapparatus including a rotating actuator which is fixed to the surfaceplate or the exposure apparatus housing structure and generates a torquein a rotational direction, an inertial load which is connected to theactuator and moves in the rotational direction relative to the surfaceplate or the exposure apparatus housing structure in accordance with atorque of the actuator, and a driving circuit for generating a drivingcommand signal for controlling the inertial load and driving therotating actuator in accordance with the driving command signal, whereinthe rotating actuator rotates/drives the inertial load with a generatedtorque, and reduces vibrations produced in the surface plate or theexposure apparatus housing structure by applying a drive reaction forcegenerated upon rotating/driving the inertial load as a control torque tothe surface plate or the exposure apparatus housing structure.

According to the present invention, there is provided a maintenancemethod for an exposure apparatus, the maintenance method comprising: thestep of causing a vendor or user of the exposure apparatus to provide amaintenance database connected to an external network of thesemiconductor manufacturing factory; the step of allowing access fromthe semiconductor manufacturing factory to the maintenance database viathe external network; and the step of transmitting maintenanceinformation accumulated in the maintenance database to the semiconductormanufacturing factory via the external network, and maintaining theexposure apparatus on the basis of the maintenance information, whereinthe exposure apparatus includes a stage apparatus having a substrate ormaster plate as an exposure target mounted thereon and performingprecision positioning operation, and an active vibration suppressionapparatus which acts on a surface plate on which the stage apparatus ismounted or on an exposure apparatus housing structure mounted on thesurface plate to reduce vibrations of the surface plate or the exposureapparatus housing structure in a translation direction, which areproduced upon driving of the stage apparatus, the active vibrationsuppression apparatus includes an actuator which is fixed to the surfaceplate or the exposure apparatus housing structure and generates athrust, an inertial load which is connected to the actuator and isdriven relative to the surface plate or the exposure apparatus housingstructure in accordance with the thrust generated by the actuator, and adriving circuit for generating a driving command signal for controllingdriving of the inertial load and driving the actuator in accordance withthe driving command signal, and wherein the actuator drives the inertialload with the generated thrust, and applies a drive reaction forcegenerated upon driving of the inertial load as a control force to thesurface plate or the exposure apparatus housing structure to reducevibrations produced in the surface plate or the exposure apparatushousing structure.

According to the present invention, there is provided a maintenancemethod for an exposure apparatus, the maintenance method comprising: thestep of causing a vendor or user of the exposure apparatus to provide amaintenance database connected to an external network of thesemiconductor manufacturing factory; the step of allowing access fromthe semiconductor manufacturing factory to the maintenance database viathe external network; and the step of transmitting maintenanceinformation accumulated in the maintenance database to the semiconductormanufacturing factory via the external network, and maintaining theexposure apparatus on the basis of the maintenance information, whereinthe exposure apparatus includes a stage apparatus having a substrate ormaster plate as an exposure target mounted thereon and performingprecision positioning operation, and an active vibration suppressionapparatus which acts on a surface plate on which the stage apparatus ismounted or an exposure apparatus housing structure mounted on thesurface plate to reduce vibrations of the surface plate or the exposureapparatus housing structure in a rotational direction which are producedupon driving of the stage apparatus, the active vibration suppressionapparatus including a rotating actuator which is fixed to the surfaceplate or the exposure apparatus housing structure and generates a torquein a rotational direction, an inertial load which is connected to theactuator and moves in the rotational direction relative to the surfaceplate or the exposure apparatus housing structure in accordance with atorque of the actuator, and a driving circuit for generating a drivingcommand signal for controlling the inertial load and driving therotating actuator in accordance with the driving command signal, andwherein the rotating actuator rotates/drives the inertial load with agenerated torque, and reduces vibrations produced in the surface plateor the exposure apparatus housing structure by applying a drive reactionforce generated upon rotating/driving the inertial load as a controltorque to the surface plate or the exposure apparatus housing structure.

Preferably, the above exposure apparatus further comprises a display fordisplaying maintenance information, a network interface which isconnected to a computer network to communicate the maintenanceinformation, and a computer for executing the communication by usingnetwork software, and can perform data communication of maintenanceinformation of the exposure apparatus via the computer network.

Preferably, in the above exposure apparatus, the network softwareprovides, on the display, a user interface which is connected to theexternal network of the factory in which the exposure apparatus isinstalled and used to access the maintenance database provided by thevendor or user of the exposure apparatus, and allows acquisition ofinformation from the database via the external network.

Other features and advantages of the present invention will be apparentfrom the following description taken in conjunction with theaccompanying drawings, in which like reference characters designate thesame or similar parts throughout the figures thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate embodiments of the invention and,together with the description, serve to explain the principles of theinvention.

FIG. 1 is a view showing the arrangement of an active vibrationsuppression apparatus according to the first embodiment of the presentinvention;

FIG. 2 is a view showing the arrangement of a linear-acting vibrationsuppression unit in FIG. 1;

FIG. 3 is a perspective view showing a linear-acting actuator and aninertial load in FIG. 1;

FIG. 4 is a graph showing an example of a nonlinear function applied tothe active vibration suppression apparatus according to the firstembodiment of the present invention;

FIG. 5 is a block diagram showing an example of the arrangement of acompensation computation section applied to the active vibrationsuppression apparatus according to the first embodiment of the presentinvention;

FIG. 6 is a block diagram showing an example of the arrangement of afeedforward compensation computation section applied to the activevibration suppression apparatus according to the first embodiment of thepresent invention;

FIG. 7 is a graph showing the relationship between a nonlinear functionand a linear function applied to the active vibration suppressionapparatus according to the first embodiment of the present invention;

FIG. 8 is a view showing the arrangement of an active vibrationsuppression apparatus according to the second and third embodiments ofthe present invention;

FIGS. 9A and 9B are graphs showing the simulation results obtained fromthe apparatus according to the present invention;

FIG. 10 is a view showing an example of the arrangement of asemiconductor exposure apparatus having the active vibration suppressionapparatus according to the third embodiment of the present invention;

FIG. 11 is a view showing the fourth embodiment of the presentinvention;

FIG. 12 is a view showing the arrangement of a rotational vibrationsuppression unit according to an embodiment of the present invention;

FIG. 13 is a perspective view showing a rotating actuator and flywheelaccording to an embodiment of the present invention;

FIG. 14 is a view showing the arrangement of an apparatus according tothe fifth embodiment of the present invention;

FIG. 15 is a perspective view for explaining an example of the vibrationmode of a structure in a semiconductor exposure apparatus;

FIG. 16 is a perspective view for explaining another example of thevibration mode of the structure in the semiconductor exposure apparatus;

FIG. 17 is a perspective view showing an example of an actuator actingin the vertical direction, which is used in a linear-acting vibrationsuppression apparatus;

FIG. 18 is a perspective view showing an example of an actuator actingin the horizontal direction, which is used in the linear-actingvibration suppression apparatus;

FIG. 19 is a view showing the concept of a semiconductor deviceproduction system using the apparatus according to the present inventionwhen viewed from a given angle;

FIG. 20 is a view showing the concept of the semiconductor deviceproduction system using the apparatus according to the present inventionwhen viewed from another given angle;

FIG. 21 is a view showing a specific example of a user interface;

FIG. 22 is a flow chart showing the flow of a device manufacturingprocess; and

FIG. 23 is a flow chart for explaining a wafer process.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will now be described indetail in accordance with the accompanying drawings.

First Embodiment

In the first embodiment of the present invention, an active vibrationsuppression apparatus will be described below, which reduces vibrationsthat are produced in a precision equipment mount vibration isolationbase or in an object mounted on a vibration isolation base, and affectprecision equipment, such as a semiconductor exposure apparatus.

FIG. 1 is a view showing the arrangement of an active vibrationisolation apparatus according to the first embodiment of the presentinvention. In the active vibration suppression apparatus according tothis embodiment, a vibration suppression target is a vibration isolationbase 1 supported to be vibration-isolated by support mechanisms 2 suchas air springs. In a semiconductor exposure apparatus, an exposureapparatus body supported by a vibration isolation apparatus or avibration isolation base on which a stage apparatus having a substrate(silicon wafer, or the like) or master plate (reticle, or the like)mounted thereon, and which performs precision positioning operation, isa vibration suppression target equivalent to that in this embodiment.The embodiment will be described below with reference to FIG. 1.

The active vibration suppression apparatus according to this embodimentincludes a linear-acting vibration suppression unit 50 for applying acontrol force to the vibration isolation base 1 as a vibrationsuppression target, a vibration detection unit 3 for detecting thevibrations of the vibration isolation base 1 as the vibrationsuppression target, a compensation computation section 4 for performingan appropriate compensation computation for a signal corresponding tothe vibrations of the vibration suppression target, a feedforwardcompensation computation section 5 for performing a compensationcomputation for the operation state of equipment, such as an X-Y stagemounted on the vibration isolation base 1, or a signal from a controlsection for the equipment, and the like. For each support mechanism 2, avibration isolation support mechanism using an elastic member, such asan air spring or rubber, can be used. In addition, for each supportmechanism 2, an active vibration isolation apparatus can also be used,which detects the vibrations of the vibration isolation base 1 with asensor, and performs control to reduce the vibrations by using anactuator for applying a control force to the vibration isolation base 1on the basis of the signal obtained by compensating for the resultantsignal.

As shown in FIG. 2, the linear-acting vibration suppression unit 50 isfixed on the vibration isolation base 1 as the vibration suppressiontarget and is comprised of a linear-acting actuator 51 for generating athrust in accordance with a driving signal, an inertial load 52 that isconnected to the linear-acting actuator 51 and moves in a straightdirection relative to the vibration isolation base 1, a base member 53,a stopper 54 for restricting the operation of the inertial load 52within a predetermined range, a driving circuit 55 for the linear-actingactuator 51, and the like. The driving circuit 55 may not be mounted onthe vibration isolation base 1 and may be kept apart from thelinear-acting actuator 51, inertial load 52, and the like.

FIG. 3 is a perspective view showing the linear-acting actuator 51,inertial load 52, and the like. The inertial load 52 is supported by alinear guide, whose detailed arrangement is omitted in FIG. 3, and thelike, such that it can move in the direction indicated by an arrow A inFIG. 3. The inertial load 52 is driven in the straight directionindicated by the arrow A by the thrust generated by the linear-actingactuator 51. The linear-acting actuator 51 is comprised of a stator 51 aand movable part 51 b. The stator 51 a is rigidly fastened to thevibration isolation base 1, whereas the movable part 51 b is connectedto the inertial load 52 and configured to be movable in a straightdirection relative to the vibration isolation base 1.

As the linear-acting actuator 51 shown in FIG. 3, for example, anelectromagnetic linear motor can be suitably used, which has a coilwinding and permanent magnet mounted on the stator 51 a and movable part51 b, respectively, and generates a thrust in the direction indicated bythe arrow A in FIG. 3 using the interaction between a current flowing inthe coil winding and the magnetic field generated by the permanentmagnet. The thrust generated by such an electromagnetic linear motor canbe easily controlled by controlling the current flowing in the coilwinding by using the driving circuit 55.

Obviously, as the linear-acting actuator 51, other various types ofactuators can be used, e.g., an actuator constituted by a rotatingelectromagnetic actuator such as a DC servo motor and a feed screwmechanism for converting the torque produced by the actuator into athrust in a straight direction and moving the inertial load 52 in thestraight direction.

This linear-acting actuator 51 is fixed to the vibration isolation base1 as the vibration suppression target through the base member 53, andgenerates a thrust to displace the inertial load 52 relative to thevibration isolation base 1 as the vibration suppression target. When athrust is generated in the linear-acting actuator 51 to displace theinertial load 52, a reaction force of the thrust acting on the inertialload 52 acts on the vibration suppression target. The vibrationsuppression apparatus according to this embodiment uses this reactionforce as a control force for vibration control. That is, this vibrationsuppression apparatus adjusts the driving force generated by thelinear-acting actuator 51 to drive the inertial load 52 so as to controla thrust applied as a reaction force to the vibration suppressiontarget.

As the vibration detection unit 3 for detecting the vibrations of thevibration suppression target, i.e., the vibration isolation base 1, anacceleration sensor, velocity sensor, or the like, can be used.

The operation of the vibration suppression apparatus according to thisembodiment will be described next with reference to FIG. 1.

The apparatus according to this embodiment performs the controloperation of feeding back, to the linear-acting vibration suppressionunit 50, the signal obtained by compensating for a signal correspondingto the vibrations of the vibration isolation base 1 as the vibrationsuppression target obtained by using the vibration detection unit 3 andcompensation computation section 4, the control operation of feedingforward, to the linear-acting vibration suppression unit 50, theoperation state of equipment such as an X-Y stage 45 mounted on thevibration isolation base 1 or information from a control section for theequipment by using the feedforward compensation computation section 5,and the like.

Feedback control operation using the vibration detection unit 3,compensation computation section 4, and the like, will be describedfirst.

In the feedback control operation, the vibration detection unit 3mounted on the vibration isolation base 1 is used to detect vibrationsproduced in the vibration isolation base 1 by vibration transmissionfrom the apparatus mount pedestal or the operation of equipment such asthe X-Y stage 45 mounted on the vibration isolation base 1, and thecompensation computation section 4 performs an appropriate compensationcomputation for the resultant detection signal. The linear-actingvibration suppression unit 50 is then driven on the basis of theresultant signal to reduce/suppress the vibrations of the vibrationisolation base 1.

In the apparatus according to this embodiment, the compensationcomputation section 4 executes a compensation computation by a nonlinearcomputation. Obviously, as this nonlinear computation, various types ofcomputations can be used in accordance with applications and purposes.Consider a case wherein a linear compensation computation typified byproportional compensation or integral compensation is performed for asignal corresponding to the vibrations of the vibration suppressiontarget, i.e., the vibration isolation base 1, which are detected by thevibration detection unit 3, and then a nonlinear compensationcomputation is performed for the resultant signal.

As a case of a linear compensation computation to be performed by thecompensation computation section 4 to reduce the vibrations of thevibration isolation base 1, a case wherein a damping property isprovided to the natural vibrations of the vibration system constitutedby the vibration isolation base 1 and the support mechanism 2 thatvibration-isolates/supports the vibration isolation base 1 will bedescribed below. To provide a damping property to the natural vibrationsof the vibration system constituted by the vibration isolation base 1and support mechanism 2, a computation may be performed to apply acontrol force proportional to the vibration velocity of the vibrationisolation base 1 to the vibration isolation base 1. When an accelerationsensor is used as the vibration detection unit 3 and an electromagneticmotor with a high response property is used as the linear-actingactuator 51 of the linear-acting vibration suppression unit 50, thecompensation computation section 4 may mainly perform an integralcompensation computation as a compensation computation for a signalcorresponding to the vibration acceleration of the vibration isolationbase 1, which is detected by the vibration detection unit 3. Theelectromagnetic motor generally exhibits an excellent response propertyup to a sufficiently high frequency as compared with the naturalfrequency of the vibration system constituted by the vibration isolationbase 1 and support mechanism 2. For this reason, in a frequency regionnear the natural frequency, which requires a damping property, theelectromagnetic motor receives a driving current command and caninstantaneously generate a thrust almost equal to the thrust designatedby the signal. The compensation computation section 4 may performintegral computation for the acceleration signal of the vibrationisolation base 1, detected by the vibration detection unit 3, to obtaina signal proportional to the velocity. Obviously, according to the sameconcept as described above, when a velocity sensor is used as thevibration detection unit 3, the compensation computation section 4 mayperform a proportional compensation computation.

In this case, the compensation computation section 4 performs a linearcompensation computation to provide a damping property to the naturalvibrations of the vibration system constituted by the vibrationisolation base 1 and support mechanism 2. However, signals associatedwith acceleration, velocity, and vibration may be properly combined orlinear compensation computations other than an integral compensationcomputation and proportional compensation computation, e.g., adifferential compensation computation, a phase-lead compensationcomputation, and a phase-lag compensation computation, may be applied orused together to control the vibrations of the vibration isolation base1 to an appropriate state.

In the active vibration suppression apparatus according to thisembodiment, a nonlinear computation is further performed for the linearcompensation computation result obtained in this manner. In this case, anonlinear computation with an input/output characteristic like thatshown in FIG. 4 is performed for the above linear compensationcomputation result, and the linear-acting vibration suppression unit 50is controlled by using the computation result. The nonlinear computationshown in FIG. 4 is a monotonously increasing nonlinear function, anexample of the function for outputting the signal obtained bymultiplying an input signal by a gain which decreases with an increasein distance from the neutral point of the input signal. Letting x be theinput and y be the output, this computation is represented by

$\begin{matrix}{y = {K_{1}\left( {\frac{1}{1 + {\exp\left( {{- K_{2}}x} \right)}} - 0.5} \right)}} & (1)\end{matrix}$where K₁ and K₂ are constants, and K₂ is a positive constant.

Letting x be the input and y be the output, this equation uses anonlinear function called a sigmoid function expressed by

$\begin{matrix}{y = \frac{1}{1 + {\exp\left( {- x} \right)}}} & (2)\end{matrix}$

Note that the input/output characteristic shown in FIG. 4 can bedescribed by a nonlinear function which monotonously increases with thepositive constant K₁. Obviously, in some cases, a nonlinear computationdescribed by a nonlinear function, which monotonously decreases with anegative constant K₁, can be used.

According to the function represented by equation (1), as the absolutevalue of the input x increases, the absolute value of the output y/inputx ratio decreases. If, for example, K₁=1 and K₂=1, y/x=0.23 for x=1, buty/x=0.19 for x=2. That is, this function has an input/outputcharacteristic in which as the input increases, the absolute value ofthe gain of output y/input x decreases.

Assume that such a nonlinear computation is used. In this case, if thesignal obtained by the above linear compensation computation, i.e., theinput to a nonlinear computation, is small, an output signal equivalentto y=K₃x, as shown in FIG. 7, is generated. If, however, the signalobtained by the linear compensation computation is large, an outputsignal similar to linear function y=K₄x, proportional to a gain K₄smaller in absolute value than K₃, is generated. That is, if the levelof an input signal to the compensation computation section is high, asignal equivalent to that obtained upon suppression of a control gain isoutput as compared with a case wherein the level is low.

The apparatus according to this embodiment can therefore obtain acompensation computation result that ensures a high control gain in asufficiently wide range with respect to the stroke range in which theoperation of the inertial load 52 is restricted by the stopper 54 anddecreases the control gain to prevent the inertial load 52 fromexceeding the stroke range (stroke over) in a range in which a largecontrol force is required.

FIG. 5 is a computation block diagram of the compensation computationsection 4 described above. The compensation computation section 4 isformed by a series circuit of a linear compensation computation circuit4 a for performing an integral compensation computation, or the like,and a nonlinear compensation computation circuit 4 b for performing anonlinear compensation computation like equation (1).

Feedback control operation of the active vibration suppression apparatusaccording to this embodiment can be implemented by controlling thelinear-acting vibration suppression unit 50 on the basis of the signalobtained by the compensation computation section 4 for performingcompensation computations, including a nonlinear computation. Note thatthe nonlinear computation performed by the compensation computationsection 4 is not limited to equation (1). Obviously, the compensationcomputation section 4 may be formed by only the nonlinear compensationcomputation circuit 4 b instead of being constituted by the linearcompensation computation circuit 4 a and nonlinear compensationcomputation circuit 4 b, as in this case.

Feedforward control operation using the feedforward compensationcomputation section 5 will be described next. The feedforwardcompensation computation section 5 serves to generate a signal forappropriate vibration control by performing compensation computation fora signal representing the operation state of equipment such as the X-Ystage mounted on the vibration isolation base 1. Feedforward controloperation will be described in detail below.

Assume that an equipment having a driving means such as the X-Y stage 45is mounted on the vibration isolation base 1, as shown in FIG. 1. ThisX-Y stage 45 is driven by an electromagnetic linear motor, or the like.The electromagnetic linear motor for driving the X-Y stage 45 is driventhrough an X-Y stage driving circuit 47 on the basis of a signal from anX-Y stage control section 46.

The feedforward compensation computation section 5 performs appropriatecomputation processing to make the linear-acting vibration suppressionunit 50 effectively reduce/suppress vibrations produced in the vibrationisolation base 1 by the drive reaction force of the X-Y stage 45 on thebasis of a signal from the X-Y stage control section 46 or a signalassociated with the driven state of the X-Y stage 45.

This feedforward compensation computation can be implemented by makingthe feedforward compensation computation section 5 perform anappropriate compensation computation by using a bandpass filter, or thelike, on the basis of a signal proportional to the drive acceleration ofthe X-Y stage 45 or its drive reaction force, so as to apply a controlforce proportional to the signal in a desired control band. If theinertial load 52 exceeds the stroke range limited by the stopper 54 inrealizing this feedforward control operation, a nonlinear compensationcomputation like the one represented by equation (1) is performed forsuch a linear compensation computation result, and the linear-actingvibration suppression unit 50 is controlled on the basis of theresultant signal. Basically, therefore, control is performed by drivingthe linear-acting vibration suppression unit 50 on the basis of a signalproportional to the drive acceleration of the X-Y stage 45 or its drivereaction force. Assume that when this signal is directly used, theinertial load 52 exceeds the stroke range, and the operation of thecontrol system is impaired. In this case, to ensure stability, propercontrol operation, a nonlinear computation like equation (1) isperformed for this signal, and the linear-acting vibration suppressionunit 50 is driven by using the resultant signal. With this operation,the vibration suppression apparatus according to this embodiment canobtain a compensation computation result that ensures a high controlgain in a sufficiently wide range with respect to the allowable strokerange in which the operation of the inertial load 52 is limited by thestopper 54, and decreases the control gain to prevent the inertial load52 from exceeding the stroke range in a range in which a large controlforce is required.

FIG. 6 is a computation block diagram of the feedforward compensationcomputation section 5 described above, which includes a nonlinearcompensation computation. The feedforward compensation computationsection 5 is formed by a series circuit of a linear compensationcomputation circuit 5 a for performing a proportional compensationcomputation, or the like, and a nonlinear compensation computationcircuit 5 b for performing a nonlinear computation like equation (1).

The feedforward control operation of the active vibration suppressionapparatus according to this embodiment is implemented by controlling thelinear-acting vibration suppression unit 50 on the basis of the signalobtained by the feedforward compensation computation section 5,including such a nonlinear computation. Note that the nonlinearcomputation performed by the feedforward compensation computationsection 5 is not limited to equation (1). Obviously, the feedforwardcompensation computation section 5 may be formed by only the nonlinearcompensation computation circuit 5 b instead of being constituted by thelinear compensation computation circuit 5 a and nonlinear compensationcomputation circuit 5 b, as in this case.

As described above, the apparatus according to this embodiment canperform compensation computations by computation processing includingnonlinear computations in both the control operation of detecting thevibrations of the vibration isolation base 1 as the vibrationsuppression target, compensating for the resultant detection signal, andfeeding back the resultant signal to the linear-acting vibrationsuppression unit 50 and the control operation of feeding forwardinformation, such as the operation state of equipment mounted on thevibration isolation base 1, by using the feedforward compensationcomputation section 5. Although feedback control operation andfeedforward control operation have been separately described, bothfeedback control operation and feedforward control operation can besimultaneously performed by driving the linear-acting vibrationsuppression unit 50 on the basis of the signal obtained by adding thetwo compensation computation results. Obviously, control may beperformed by only one of feedback control operation and feedforwardcontrol operation. In addition, only one of feedback control operationand feedforward control operation may be performed on the basis ofcompensation computation processing including a nonlinear computation,as needed.

The conventional apparatus designed to reduce/suppress the vibrations ofa vibration suppression target by using an apparatus similar to thelinear-acting vibration suppression unit 50 is configured to performcontrol by using only the linear compensation computation resultdescribed above.

However, the movable stroke of the inertial load 52 on the linear-actingvibration suppression unit 50 is finite. For this reason, when largevibrations are caused in the vibration suppression target, and a largecontrol force is required to suppress the vibrations, the inertial load52 may exceed this stroke range, resulting in function failure. If theinertial load 52 exceeds the allowable stroke range, the inertial load52 collides with the stopper 54 to restrict the operation range of theinertial load 52. As a consequence, large impact vibrations areproduced. If the impact vibrations are detected by the vibrationdetection unit 3, and a compensation signal is fed back to thelinear-acting vibration suppression unit 50, a large signal originatingfrom the impact vibrations is input to the linear-acting vibrationsuppression unit 50. This may cause an unstable control state. In acontrol scheme based on only linear compensation computations, toprevent inconveniences caused by collision of the inertial load 52 withthe stopper 54, the gain of a linear compensation computation such asintegral compensation or proportional compensation performed by thecompensation computation section 4 must be decreased to a certainextent. Although the stable operation of the vibration suppressionapparatus can be ensured by this operation, the vibration suppressioneffect is also reduced.

In contrast to this, in the apparatus described in this embodiment, arelatively high control gain can be used to control vibrations that canbe suppressed by a relatively small control force that falls within thesufficiently wide range with respect to the stroke range in which theoperation of the inertial load 52 is limited by the stopper 54 by usinga compensation computation including a nonlinear computation processlike that described above. Therefore, an excellent vibration reducingeffect can be obtained. If large vibrations are produced, this apparatusperforms operation equivalent to a control operation with a relativelylow control gain. For this reason, the control force generated by thelinear-acting vibration suppression unit 50 is suppressed, and stablevibration control can be performed without causing any stroke over ofthe inertial load 52.

According to the active vibration suppression apparatus of thisembodiment, even if severe restrictions are imposed on the movablestroke, mass, and the like, of an inertial load, both a vibrationsuppressing effect and stable operation in the presence of largevibrations can be realized, and maximum vibration suppressionperformance can be obtained under the restrictions.

Second Embodiment

FIG. 8 is a view showing an example of the arrangement of an apparatusaccording to the second embodiment of the present invention, which isconfigured to reduce the vibrations of a structure 6 mounted on avibration isolation base 1.

In the first embodiment, the apparatus according to the presentinvention has been described in detail with reference to the casewherein the vibration isolation base 1 is a vibration suppressiontarget. The second embodiment will exemplify the case wherein localresonance vibrations produced in the structure 6 fastened to thevibration isolation base 1 with relatively high rigidity arereduced/suppressed by an active vibration suppression apparatusaccording to the present invention. A vibration suppression target inthis embodiment is not the natural vibrations of the vibration systemconstituted by the vibration isolation base 1 and a support mechanism 2,but is the structural resonance vibrations of the structure 6 fastenedto the vibration isolation base 1 with relatively high rigidity. In asemiconductor exposure apparatus, a structure that supports an opticalunit, measuring system, and the like, corresponds to this structure 6.

The arrangement of the apparatus of this embodiment differs from that ofthe first embodiment in that a linear-acting vibration suppression unit50 and vibration detection unit 3 are mounted on the structure 6fastened to the vibration isolation base 1, instead of being mounted tothe vibration isolation base 1. This embodiment differs from the firstembodiment in that the vibration detection unit 3 detects the vibrationsof the structure 6 serving as a vibration suppression target, and thelinear-acting vibration suppression unit 50 applies a control force tothe structure 6. In other respects, the constituent elements andoperation of this embodiment are basically the same as those of thefirst embodiment. However, the operations of a compensation computationsection 140 and feedforward compensation computation section 150 areslightly different from those in the first embodiment, and hence onlythese portions will be described below.

The compensation computation section 140 according to this embodimentwill be described first.

The vibration system constituted by the vibration isolation base 1 andsupport mechanism 2, which serves as the vibration suppression target inthe first embodiment, has a relatively low natural frequency of 10 Hz orless. The structure 6 serving as a vibration suppression target in thisembodiment structurally resonates at a frequency of several tens of Hzor more. The control force required by the linear-acting vibrationsuppression unit 50 to reduce/suppress the resonance vibrations of thestructure 6 contains a relatively high frequency component as comparedwith the first embodiment. The control force generated by thelinear-acting vibration suppression unit 50 is proportional to the drivereaction force of an inertial load 52, i.e., the operating accelerationof the inertial load 52. As is generally known, even if given objectsoperate at the same acceleration, the operation displacement amount ofone of the objects which exhibits a higher operating frequency componentbecomes smaller. For this reason, the operation range of the inertialload 52, which is required to reduce/suppress the resonance vibrationsof the structure 6, is narrower than that in the first embodiment,resulting in a decrease in the possibility of an occurrence of strokeover. The apparatus according to this embodiment can, therefore,effectively reduce/suppress the vibrations of the structure 6 whilesuppressing the operation stroke of the inertial load 52 to be small byextracting a structural resonance component from the vibrations of thestructure 6. The natural vibration component with a relatively lowfrequency of the vibration system constituted by the vibration isolationbase 1 and support mechanism 2 extracted from the control signal byperforming appropriate filter processing for the signal output from thevibration detection unit 3 or adjusting the rigidity with which theinertial load 52 is kept at a predetermined neutral position by using apassive/active means.

If, however, the natural frequency of the vibration system constitutedby the vibration isolation base 1 and support mechanism 2 is relativelynear the resonance frequency of the structure 6, it is difficult toeliminate the influence of the natural vibrations of the vibrationsystem constituted by the vibration isolation base 1 and supportmechanism 2 even by performing these processes. As a result, thislow-frequency component is input to the control system of the activevibration suppression apparatus, and increases the operation stroke ofthe inertial load 52.

In this embodiment, therefore, a compensation computation including anonlinear computation is performed as in the first embodiment. Morespecifically, when the resonance vibrations of the structure 6 are to bedamped by feeding back a control force proportional to the vibrationvelocity of the structure 6, a nonlinear function like equation (1),which has been described in detail in the first embodiment, is used.That is, the apparatus according to this embodiment performs a linearcompensation computation for a detection signal from the vibrationdetection unit 3, and performs a nonlinear computation like equation (1)for the computation result, thereby controlling the linear-actingvibration suppression unit 50 by using the resultant signal. Since thisembodiment is aimed at reducing/suppressing the resonance vibrations ofthe structure 6, in order to minimize the influence of the low-frequencynatural vibrations of the vibration system constituted by the vibrationisolation base 1 and support mechanism 2, appropriate filter processingis preferably performed as a pre-process for a linear compensationcomputation.

With this control, even if the inertial load 52 may be greatly swung bya vibration component, which is not a vibration suppression target, anexcellent vibration reducing effect can be ensured with a relativelyhigh control gain with respect to vibrations that can be controlled by acontrol force falling within a sufficiently wide range with respect tothe stroke range in which the operation of the inertial load 52 islimited by a stopper 54. If large vibrations are produced, stablevibration control can be realized without any stroke over of theinertial load 52 by operation equivalent to a control operation with arelatively low control gain. That is, maximum vibration suppressionperformance can be obtained under restrictions.

Control operation based on the same concept as described above can alsobe applied to the feedforward compensation computation section 150. Thatis, a compensation computation using both a linear compensationcomputation and a nonlinear compensation computation can be performed.

Assume that the structure 6 serving as the vibration suppression targetis not fastened to an X-Y stage 45 having a driving means withsufficient rigidity, unlike in this embodiment, and resonance vibrationsare produced in the structure 6. In this case, the apparatus mustperform a compensation computation different from that in the firstembodiment, i.e., perform a linear compensation computation, on thebasis of a signal proportional to the drive acceleration of the X-Ystage 45 or its drive reaction force, to apply a control forceproportional to the signal to the vibration isolation base 1 in adesired control band. In consideration of the mechanical rigiditybetween the X-Y stage 45 and the structure 6, compensation must beperformed to generate a signal for allowing the linear-acting vibrationsuppression unit 50 to cancel the vibrations produced in the structure 6by the operation of the X-Y stage 45. This embodiment is different fromthe first embodiment in this point.

Note that the maximum vibration suppression performance can be obtainedunder the restriction of the allowable stroke of the inertial load 52 byperforming a nonlinear compensation computation using the feedforwardcompensation computation section 150 as in the first embodiment. This isa significant advantage obtained by the present invention.

FIGS. 9A and 9B show the simulation results obtained when the resonancevibrations of a structure of this type are reduced/suppressed byfeedback control operation using the compensation computation section140. Referring to FIGS. 9A and 9B, the abscissa represents the timeelapsed since the occurrence of vibrations in the vibration suppressiontarget, and the ordinate represents the acceleration of the vibrationsuppression target in FIG. 9A, and the displacement amount of theinertial load in FIG. 9B. Referring to FIGS. 9A and 9B, each curveindicated by “(I)” represents the control result based on the result ofa compensation computation including a nonlinear compensationcomputation, and each curve indicated by “(II)” represents the controlresult based on only a conventional linear compensation computation. Inthis case, in a compensation computation including a nonlinearcompensation computation, a compensation computation based on anonlinear function represented by equation (1) is performed for a signalsimilar to the one indicated by “(II)” for which a linear compensationcomputation has been performed.

As is apparent from this result, the vibrations of the vibrationsuppression target can be quickly reduced without increasing the maximumamount of displacement from the neutral position of the inertial load 52by properly using a nonlinear compensation computation.

As described above, according to the active vibration suppressionapparatus of this embodiment, even if severe restrictions are imposed onthe movable stroke, mass, and the like, of an inertial load, both avibration suppressing effect and stable operation in the presence oflarge vibrations can be realized, and the resonance vibrations of thestructure mounted on the vibration isolation base can be stably andeffectively reduced/suppressed.

Third Embodiment

The third embodiment of the present invention will exemplify thefollowing semiconductor exposure apparatus having the active vibrationsuppression apparatus shown in FIG. 8 to reduce vibrations that affectthe exposure performance.

In the third embodiment, an apparatus will be described, which has anactive vibration suppression apparatus mounted on a structure having acantilever structure, which is a component of a semiconductor exposureapparatus to reduce/suppress structural vibrations centered on thecantilever fulcrum of the structure. In this case, an embodiment will bedescribed, in which a structure having a cantilever support structureand serving as a vibration suppression target is a mechanical structureas a component of an illumination optical unit for emitting exposurelight to expose a silicon wafer as a substrate to a circuit patternformed on a reticle as a master plate through an optical lens system.

FIG. 10 is a view showing an embodiment of the arrangement of asemiconductor exposure apparatus.

In the apparatus shown in FIG. 10, a wafer stage 94, on which a siliconwafer as a substrate which is to be exposed to a circuit pattern and astage surface plate 93 on which the wafer stage 94 is mounted, areplaced on an apparatus mount pedestal 100 through a vibration isolationsupport mechanism such as a vibration isolation apparatus 92. Both thestage surface plate 93 and a lens barrel surface plate 97 are rigidlyfastened to a surface plate 99 and supported by the vibration isolationapparatus 92. A reticle stage 95 and optical lens system 96 are mountedon the lens barrel surface plate 97. The optical lens system 96 is usedto project the pattern of a master plate called a reticle, having acircuit pattern, which is mounted on the reticle stage 95, onto asilicon wafer.

The vibration isolation apparatus 92 is not directly installed on theapparatus mount pedestal 100 but is fixed to a pedestal structure 91called a pallet or base plate. The pedestal structure 91 serves as areference for maintaining the relative positional relationship betweenthe devices mounted on the vibration isolation apparatus 92 andcomponents, such as a wafer feeder, reticle changer, and light source(which are not shown in FIG. 10) and not mounted on the vibrationisolation apparatus 92, or a pedestal member on which the overallsemiconductor exposure apparatus is mounted to be transportedaltogether. A level adjusting mechanism with high rigidity (not shown inFIG. 10), called a leveling block, or the like, is provided under thepedestal structure 91. By adjusting this mechanism in accordance withthe condition of the apparatus mount pedestal 100, the semiconductorexposure apparatus can be installed in a predetermined posture.

As the vibration isolation apparatus 92, an active vibration isolationapparatus, or the like, is used, which detects the vibrations of thesurface plate 99 with a sensor, or the like, and controls an actuatorfor applying a control force to the surface plate 99 on the basis of thesignal obtained by compensating for the detection signal, therebyreducing the vibrations.

The optical lens system 96 is set between the reticle stage 95 and thewafer stage 94. A reticle is irradiated with exposure light emitted froman illumination optical unit 98 to project a circuit pattern formed onthe reticle onto a silicon wafer through the optical lens system 96 byexposure.

Semiconductor exposure apparatuses are classified into cell projectiontype apparatuses (steppers), scan exposure type apparatuses (scanners),and the like, according to the exposure schemes. In a case of a cellprojection type apparatus, a predetermined exposure area, e.g., an areacorresponding to one integrated circuit such as an IC, is exposed atonce while the wafer stage 94 is sequentially driven by an intermittentdriving scheme called a step-and-repeat scheme. In a case of a scanexposure type apparatus, the wafer stage 94 and reticle stage 95 aresynchronously operated to scan/expose a wafer in a circuit patternformed on a reticle. In the case of the scan exposure type apparatus,the reticle stage 95 is driven with a large operation by a relativelylarge driving force as compared with the driving force required in thecell projection type apparatus.

Such a semiconductor exposure apparatus is apt to be easily affected bythe vibrations produced when the wafer stage 94 or reticle stage 95 isdriven and vibrations are transmitted from the apparatus mount pedestal100. For this reason, in this embodiment, vibrations produced in astructure as a component of the semiconductor exposure apparatus arereduced/suppressed by using an active vibration suppression apparatus tobe described below. This embodiment will exemplify the case whereinvibrations such as structural resonance produced in a mechanicalstructure as a component of the illumination optical unit 98, arereduced/suppressed.

The third embodiment of the present invention will be described belowwith reference to a case wherein an active vibration suppressionapparatus according to the present invention is applied to thesemiconductor exposure apparatus having the arrangement shown in FIG.10. For the sake of convenience, the active vibration suppressionapparatus will be described with reference to FIG. 8.

The active vibration suppression apparatus schematically shown in FIG. 8is comprised of a vibration isolation base 1, a support mechanism 2 forvibration-isolating/supporting the vibration isolation base 1, an X-Ystage 45 mounted on the vibration isolation base 1, a structure 6fastened to the vibration isolation base 1 with relatively highrigidity, and the like. The vibration isolation base 1, supportmechanism 2, and structure 6 respectively correspond to the surfaceplate 99, vibration isolation apparatus 92, and illumination opticalunit 98 described with reference to FIG. 10. The X-Y stage 45corresponds to one of the wafer stage 94 and reticle stage 95. The waferstage 94 and reticle stage 95 are respectively mounted on the stagesurface plate(s) 93 and lens barrel surface plate 97. These surfaceplates 93 and 97 are rigidly fastened to the surface plate 99. Sincethese stage apparatuses are equivalently mounted on the surface plate 99from the viewpoint of dynamics, the X-Y stage 45 is mounted on thevibration isolation base 1 in FIG. 8.

The structure 6 has a cantilever support structure as shown in FIG. 8.

In this case, the structure 6 is set as a component of the illuminationoptical unit 98.

As described above, the illumination optical unit 98 is used to emitexposure light for projecting a circuit pattern formed on a reticle ontoa silicon wafer through the optical lens system 96, and hence, is set onan extension line from the optical lens system 96 and reticle. If,therefore, the optical axis of exposure light is set in the verticaldirection as in the semiconductor exposure apparatus shown in FIG. 10,the illumination optical unit 98 must be designed to locate an exposurelight irradiation opening immediately above the optical lens system 96and the reticle. In such cases, the structure of the illuminationoptical unit 98 must often be formed by a cantilever structure like theone schematically shown in FIG. 8, owing to the layout design ofstructures constituting the exposure apparatus.

In a structure having such an arrangement, vibrations in the rotationalmotion direction centered on the fulcrum tend to be produced. FIGS. 15and 16 show examples of rotational vibrations originating from thecantilever support structure 6. FIG. 15 shows an example of rotationalvibrations around the horizontal axis centered on the cantileverfulcrum. FIG. 16 shows an example of rotational vibrations around thevertical axis. Referring to FIGS. 15 and 16, each arrow indicates thedirection of rotational vibrations, and each chain line indicates thecenter axis of rotational vibrations. FIG. 8 shows an example of theapparatus for reducing/suppressing rotational vibrations around thevertical axis in FIG. 16.

In this embodiment, an apparatus for reducing/suppressing the vibrationsof such a structure and its operation will be described.

The apparatus having the above arrangement according to this embodimentincludes a linear-acting vibration suppression unit 50 for applying acontrol force to the structure 6 serving as a vibration suppressionobject in this case, a vibration detection unit 3 for detecting thevibrations of the structure 6, a compensation computation section 4 forperforming appropriate compensation computation processing for a signalcorresponding to the vibrations of the vibration suppression target onthe basis of an output signal from the vibration detection unit 3, afeedforward compensation computation section 5 for performingcompensation computation processing for the operation state of equipmentsuch as the X-Y stage 45 mounted on the vibration isolation base 1 or asignal from the control section of the equipment, and the like.

As shown in FIG. 2, the linear-acting vibration suppression unit 50 isfixed on the structure 6 as the vibration suppression target and iscomprised of a linear-acting actuator 51 for generating a thrust inaccordance with a driving signal, an inertial load 52 that is connectedto the linear-acting actuator 51 and moves in a straight directionrelative to the vibration isolation base 1, a base member 53, a stopper54 for restricting the operation of the inertial load 52 within apredetermined range, a driving circuit 55 for the linear-acting actuator51, and the like. The driving circuit 55 may not be mounted on thesemiconductor exposure apparatus body such as the structure 6 orvibration isolation base 1 and may be kept apart from the linear-actingactuator 51, inertial load 52, and the like.

FIG. 3 is a perspective view showing the linear-acting actuator 51,inertial load 52, and the like. The inertial load 52 is supported by alinear guide, whose detailed arrangement is omitted in FIG. 3, and thelike, such that it can move in the direction indicated by an arrow A inFIG. 3. The inertial load 52 is driven in the straight directionindicated by the arrow A by the thrust generated by the linear-actingactuator 51. The linear-acting actuator 51 is comprised of a stator 51 aand movable part 51 b. The stator 51 a is rigidly fastened to thevibration suppression target, whereas the movable part 51 b is connectedto the inertial load 52 and configured to be movable in a straightdirection relative to the vibration suppression target.

As the linear-acting actuator 51, an electromagnetic linear motor can besuitably used, which has a coil winding and permanent magnet mounted onthe stator 51 a and movable part 51 b, respectively, and generates athrust in the direction indicated by the arrow A in FIG. 3 using theinteraction between a current flowing in the coil winding and themagnetic field generated by the permanent magnet. The thrust generatedby such an electromagnetic linear motor can be easily controlled bycontrolling the current flowing in the coil winding by using the drivingcircuit 55.

Obviously, as the linear-acting actuator 51, other various types ofactuators can be used, e.g., an actuator constituted by a rotatingelectromagnetic actuator, such as a DC servo motor, and a feed screwmechanism for converting the torque produced by the actuator into athrust in a straight direction to move the inertial load 52 in thestraight direction.

As shown in FIG. 2, this linear-acting actuator 51 is fixed to thestructure 6, as the vibration suppression target, through the basemember 53, and generates a thrust to displace the inertial load 52 inthe straight direction relative to the structure 6 as the vibrationsuppression target. When a thrust is generated in the linear-actingactuator 51 to displace the inertial load 52, a reaction force of thethrust acting on the inertial load 52 acts on the vibration suppressiontarget. The vibration suppression apparatus according to this embodimentuses this reaction force as a control force for vibration control. Thatis, this vibration suppression apparatus adjusts the driving forcegenerated by the linear-acting actuator 51 to drive the inertial load 52so as to control a thrust applied as a reaction force to the vibrationsuppression target.

For the vibration detection unit 3 for detecting the vibrations of thestructure 6 as the vibration suppression target, an acceleration sensor,velocity sensor, or the like, can be used.

In this embodiment, to suppress rotational vibrations like those shownin FIG. 16, the linear-acting vibration suppression unit 50 ispreferably placed to act in the tangential direction of the rotationalvibration direction, at a position as distant as possible from thecantilever fulcrum so as to efficiently act in the motion direction ofthe rotational vibrations. Likewise, the vibration detection unit 3 isplaced to efficiently detect the rotational vibrations. The vibrationdetection unit 3 is preferably placed near the linear-acting vibrationsuppression unit 50.

The operation of the vibration suppression apparatus according to thisembodiment will be described next with reference to FIG. 8.

The apparatus according to this embodiment performs the controloperation of feeding back, to the linear-acting vibration suppressionunit 50, the signal obtained by compensating for a signal correspondingto the vibrations of the structure 6 as the vibration suppression targetby using the vibration detection unit 3 and compensation computationsection 4, the control operation of feeding forward, to thelinear-acting vibration suppression unit 50, the operation state ofequipment, such as an X-Y stage 45 mounted on the vibration isolationbase 1, or information from a control section 46 for the equipment byusing the feedforward compensation computation section 5, and the like.

Feedback control operation using the vibration detection unit 3,compensation computation section 4, and the like, will be describedfirst.

In the feedback control operation, the vibration detection unit 3mounted on the structure 6 is used to detect vibrations produced in thestructure 6 by vibrations transmitted from the apparatus mount pedestalor the operation of equipment such as the X-Y stage 45 mounted on thevibration isolation base 1, and the compensation computation section 4performs an appropriate compensation computation for the resultantdetection signal. The linear-acting vibration suppression unit 50 isthen driven on the basis of the resultant signal to reduce/suppress thevibrations of the structure 6.

In order to provide a damping property for the structural vibrations ofthe structure 6, the compensation computation section 4 performs acompensation computation to make the linear-acting vibration suppressionunit 50 apply a control force proportional to the vibration velocity ofthe structure 6 to the structure 6. When an acceleration sensor is usedas the vibration detection unit 3 and an electromagnetic motor with ahigh response property is used as the linear-acting actuator 51 of thelinear-acting vibration suppression unit 50, the compensationcomputation section 4 may mainly perform an integral compensationcomputation as a compensation computation for a signal corresponding tothe vibration acceleration of the structure 6, which is detected by thevibration detection unit 3. Some electromagnetic motors exhibit anexcellent response property up to a frequency higher than the resonancefrequency of the structure 6. For this reason, in a frequency regionnear the natural frequency, which requires a damping property, theelectromagnetic motor receives a driving current command and caninstantaneously generate a thrust almost equal to the thrust designatedby the signal. The compensation computation section 4 may performintegral computation for the acceleration signal of the structure 6,detected by the vibration detection unit 3, to obtain a signalproportional to the velocity, and feed back this signal. Obviously,according to the same concepts as described above, when a velocitysensor is used as the vibration detection unit 3, the compensationcomputation section 4 may perform a proportional compensationcomputation.

In this case, the compensation computation section 4 performs acompensation computation to provide a damping property for thestructural vibrations of the structure 6. However, signals associatedwith acceleration, velocity, and vibration may be properly combined or acombination of linear compensation computations other than an integralcompensation computation and proportional compensation computation maybe applied together to control the vibrations of the structure 6 to anappropriate state.

In general, the structure 6 serving as the vibration suppression targetproduces structural resonance vibrations at a frequency of several tensof Hz or more, whereas the vibration system constituted by the vibrationisolation base 1, on which the structure 6 is fastened and mounted, andthe support mechanism 2 has a relatively low natural frequency of 10 Hzor less. For this reason, if the low-frequency natural vibrations of thevibration system constituted by the vibration isolation base 1 andsupport mechanism 2 are detected by the vibration detection unit 3 andinput to the control system of the active vibration suppressionapparatus, the operation stroke of the inertial load 52 mounted on thelinear-acting vibration suppression unit 50 may be unnecessarilyincreased due to the influence of the vibrations.

In this case, the vibration suppression target is the structuralresonance of the structure 6. Therefore, the compensation computationsection 4 performs computation processing to effectively reduce/suppressthe vibrations of the structure 6 while keeping the operation stroke ofthe inertial load 52 small by performing, in addition to thecompensation processing described above, the processing of performingappropriate filter processing for an output signal from the vibrationdetection unit 3 and cutting a natural vibration component having arelatively low frequency from the vibration system constituted by thevibration isolation base 1 and support mechanism 2 to extract astructural resonance component from the structure 6, the processing ofproviding rigidity to restore the inertial load 52 to a predeterminedneutral position by using an active means, or the like. As the means forproviding rigidity to restore the inertial load 52 to the predeterminedneutral position, a passive element such as a spring mechanism may beused.

The compensation computation performed by the compensation computationsection 4 is not limited to the linear compensation computationdescribed above. Obviously, various nonlinear computations, e.g.,nonlinear computation processing like that described in the first andsecond embodiments, can be applied in accordance with the application orpurpose.

The feedback control operation of the active vibration suppressionapparatus according to this embodiment can be implemented by controllingthe linear-acting vibration suppression unit 50 on the basis of a signalobtained by the compensation computation section 4 after performing suchcomputation processing.

Feedforward control operation using the feedforward compensationcomputation section 5 will be described next.

The feedforward compensation computation section 5 serves to generate asignal for appropriate vibration control by performing compensationcomputation for a signal representing the operation state of equipmentsuch as the X-Y stage mounted on the vibration isolation base 1.Feedforward control operation will be described in detail below.

Assume that the equipment having a driving means such as the X-Y stage45 is mounted on the vibration isolation base 1, as shown in FIG. 8.This X-Y stage 45 is driven by an electromagnetic linear motor, or thelike. The electromagnetic linear motor for driving the X-Y stage 45 isdriven by an X-Y stage driving circuit 47 on the basis of a signal fromthe X-Y stage control section 46.

The feedforward compensation computation section 5 performs appropriatecomputation processing to make the linear-acting vibration suppressionunit 50 effectively reduce/suppress vibrations produced in the structure6 by the drive reaction force of the X-Y stage 45 on the basis of asignal from the X-Y stage control section 46 or a signal associated withthe driven state of the X-Y stage 45. In consideration of the dynamiccharacteristics between the drive reaction force of the X-Y stage 45 andthe vibrations produced in the structure 6 by the reaction force, themechanical rigidity between the X-Y stage 45 and the structure 6, andthe like, the feedforward compensation computation section 5 performscompensation processing to generate a signal for canceling thevibrations produced in the structure 6 by the operation of the X-Y stage45. Obviously, this compensation computation is not limited to a linearcompensation computation, and the nonlinear computation described abovecan be applied as the compensation computation or used together.

The feedforward control operation of the active vibration suppressionapparatus according to this embodiment can be implemented by controllingthe linear-acting vibration suppression unit 50 on the basis of thesignal obtained by the feedforward compensation computation section 5 inthis manner.

Although feedback control operation and feedforward control operationhave been separately described, both feedback control operation andfeedforward control operation can be simultaneously performed by drivingthe linear-acting vibration suppression unit 50 on the basis of thesignal obtained by adding the two compensation computation results.Obviously, control may be performed by only one of feedback controloperation and feedforward control operation.

In this embodiment, one linear-acting vibration suppression unit 50 isused to reduce/suppress the vibrations of the structure 6. However, aplurality of linear-acting vibration suppression units, each identicalto the one described above, and their control systems, may be preparedto obtain a desired vibration suppressing effect.

In this embodiment, a cantilever support structure has been described asthe vibration suppression target. However, the linear-acting vibrationsuppression unit 50 may be mounted on a structure having a vibrationmode other than that of the cantilever support structure at a positioncorresponding to an antinode of the vibration mode at which vibrationsappear most noticeably in order to reduce the vibrations. In this case,as well, the vibration detection unit 3 is preferably placed near thelinear-acting vibration suppression unit 50.

In the semiconductor exposure apparatus having the above activevibration suppression apparatus, since the various structural vibrationsof the exposure apparatus, e.g., the structural resonance of acantilever support structure, such as a mechanical structure as acomponent of the illumination optical system, can be reduced/suppressed,the adverse effect of such vibrations on equipment can be reduced oreliminated. Therefore, a high-performance semiconductor exposureapparatus with a high precision and high throughput can be realized.

Fourth Embodiment

An active vibration suppression apparatus designed to act in therotational motion direction may be suitably used to reduce/suppressvibrations centered on the fulcrum of a cantilever support structure,like the vibration suppression target in the third embodiment, in therotational direction. In the fourth embodiment of the present invention,a semiconductor exposure apparatus having a structure desired tosuppress the vibrations of such a structure by using an active vibrationsuppression apparatus acting in the rotational motion direction will bedescribed.

This embodiment will be described with reference to FIG. 11.

Basically, this embodiment will also be described with reference to thecase wherein the vibrations of the semiconductor exposure apparatusshown in FIG. 10 are to be reduced. Since the same reference numerals asthose in FIG. 11 denote the same structures and functions in theapparatus in FIG. 8, and they operate in the same manner, a detaileddescription thereof will be omitted. In addition, the direction ofvibrations to be reduced/suppressed is also the same as that in thethird embodiment, which is indicated by the arrow in FIG. 16.

As shown in FIG. 11, the apparatus according to this embodiment has arotational vibration suppression unit 60 instead of the linear-actingvibration suppression unit 50 described in the third embodiment. In thisembodiment, a rotational vibration detection unit 3 c for detectingpredetermined rotational vibrations of a structure 6 as a vibrationsuppression target is used to detect the vibrations of the structure 6,and a compensation computation section 4 c is used as a means forperforming an appropriate compensation computation for a detectionsignal from the rotational vibration detection unit 3 c. A feedforwardcompensation computation section 5 c, or the like, is used as a meansfor performing a compensation computation for a signal representing theoperation state of equipment such as an X-Y stage 45 mounted on thevibration isolation base 1.

As the rotational vibration detection unit 3 c, a unit for extracting avibration component in the rotational direction of the structure 6 byperforming a computation on the basis of output signals from a pluralityof vibration sensors arranged on the structure 6, an angular velocitysensor for directly detecting the motion amount of the structure 6 inthe rotational direction, or the like, can be used. In the former case,acceleration sensors, velocity sensors, or the like, can be used as thevibration sensors. These vibration sensors are arranged such that theirdetection axes are not aligned. A signal corresponding to desiredrotational vibrations is extracted according to an arithmetic expressionon the basis of output signals from these vibration sensors.

Note that the direction of rotational vibrations to be detectedcoincides with the direction in which a torque is generated by therotational vibration suppression unit 60, i.e., the direction ofrotational vibrations to be reduced/suppressed in this case.

The rotational vibration suppression unit 60 is fixed to the structure 6and is comprised of a rotational actuator 61 for generating a torque inaccordance with a driving signal, a flywheel 62 connected to therotational actuator 61 and serving as an inertial load that moves in therotational direction relative to the structure 6, a driving circuit 63for the rotational actuator 61, and the like.

FIG. 13 is a perspective view showing the rotational actuator 61 andflywheel 62. The flywheel 62 is driven in the rotational direction bythe torque generated by the rotational actuator 61. The rotationalactuator 61 is comprised of a stator and rotator, one of which isrigidly fastened to the structure 6, while the flywheel 62 is fastenedto the other to be movable in the rotational direction relative to thestructure 6. The rotational vibration suppression unit 60 is preferablyplaced such that the extension line of its center axis passes throughthe rotation center position of the rotational vibrations of thevibration suppression target.

As the rotational actuator 61, one of various types of electromagneticmotors, e.g., a DC motor, a synchronous AC motor, an induction AC motor,and a swing electromagnetic motor, can be used. Note that theseactuators are disclosed in detail in “Active Vibration SuppressionApparatus”, Japanese Patent Application No. 2000-122731, and the like.

When this rotational actuator 61 is driven, the flywheel 62 is driven inthe rotational direction by the resultant torque, as indicated by thearrow in FIG. 13. A torque acts on the structure 6 in the directionindicated by the arrow in FIG. 11 as a result of the drive reactionforce generated in the rotational direction at this time. The rotationalvibration suppression unit 60 according to this embodiment controls thetorque acting on the structure 6 by using this reaction torque.

The operation of the apparatus according to this embodiment will bedescribed below with reference to FIG. 11.

The apparatus according to this embodiment performs the controloperation of feeding back a compensation signal for the vibrations ofthe structure 6 to the rotational vibration suppression unit 60 by usingthe rotational vibration detection unit 3 c, compensation computationsection 4 c, and the like, and the control operation of feeding forwardinformation about the operation state of equipment having a drivingmeans that influences the structure 6 to the rotational vibrationsuppression unit 60 by using the feedforward compensation computationsection 5 c.

Feedback control operation using the rotational vibration detection unit3 c and compensation computation section 4 c will be described first.

In this control operation, first of all, rotational vibrations producedin the structure 6 by the vibration transmission from the apparatusmount pedestal or the operation of equipment such as the X-Y stage 45mounted on a vibration isolation base 1 are detected by using therotational vibration detection unit 3 c. FIG. 11 shows a case wherein anangular velocity sensor is used as the rotational vibration detectionunit 3 c. The compensation computation section 4 c then performsappropriate compensation computation processing on the basis of thedetection signal obtained by the sensor.

When, for example, a damping property is to be provided for therotational vibrations of the structure 6, a computation is performed toapply a torque proportional to the angular velocity of the structure 6to the structure 6. If an angular velocity sensor is used as therotational vibration detection unit 3 c and an electromagnetic DC motor,or the like, having a high response property is used as the rotationalactuator 61 of the rotational vibration suppression unit 60, thisoperation can be realized by causing the compensation computationsection 4 c to perform a proportional compensation computation for asignal corresponding to desired rotational vibrations. A DC motor can bemanufactured to exhibit an excellent response property up to a frequencyhigher than the resonance frequency of the structure 6. For this reason,by using such a DC motor, a torque almost equal to the torque designatedby a current driving command signal can be instantaneously generated ina main control band requiring a damping property. If, therefore, thesignal obtained by performing gain compensation for the detection signalobtained by the angular velocity sensor is input to the driving circuit63 of the rotational vibration suppression unit 60, a damping propertycan be provided to the rotational vibrations of the structure 6.

Although a compensation computation in the compensation computationsection 4 c has been described with reference to the case wherein anangular velocity sensor is used to provide a damping property to therotational vibrations of the structure 6, the rotational vibrations ofthe structure 6 may be controlled to a proper state by using a sensorother than the angular velocity sensor and a physical quantity andperforming an appropriate compensation computation in accordance withthe application of the detection signal obtained by the sensor. Acompensation computation may be a nonlinear compensation computation ora compensation computation including a nonlinear computation.

Operation using the feedforward compensation computation section 5 cwill be described next.

The feedforward compensation computation section 5 c performs acompensation computation for the operation state of equipment, such asthe X-Y stage 45, mounted on the vibration isolation base 1 or a signalfrom the control section 46 for the X-Y stage, thus performing acomputation for generating a signal for appropriate vibration control.

Assume that equipment having a driving means, e.g., the X-Y stage 45, ismounted on the vibration isolation base 1, as shown in FIG. 11. This X-Ystage 45 is driven by an electromagnetic linear motor, or the like. Theelectromagnetic linear motor for driving the X-Y stage 45 is driven onthe basis of a signal from an X-Y stage control section 46 through theX-Y stage driving circuit 47. Since the X-Y stage 45 cannot always beinstalled at the center of gravity of the overall apparatus constitutedby the vibration isolation base 1 and the equipment mounted thereon, itsdrive reaction force is used to generate torques in rotationaldirections around the horizontal and vertical axes, together with areaction thrust in the translation direction, thus driving the vibrationisolation base 1 and structure 6 in the rotational direction. Toeffectively reduce/suppress the rotational vibrations of the structure 6caused by suppressing the influence of such torques, the feedforwardcompensation computation section 5 c is used to perform appropriatecomputation processing for a signal from the X-Y stage control section46 or a signal associated with the driven state of the X-Y stage 45 soas to drive the rotational vibration suppression unit 60 on the basis ofthe computation result.

The feedforward compensation computation section 5 c performs acompensation computation to generate a signal for canceling vibrationsproduced in the structure 6 by the operation of the X-Y stage 45 inconsideration of the dynamic characteristics between the drive reactionforce for the X-Y stage 45 and vibrations produced in the structure 6 bythe drive reaction force and the mechanical rigidity between the X-Ystage 45 and the structure 6. Obviously, this compensation computationis not limited to a linear compensation computation, and a nonlinearcomputation can be applied as the compensation computation or usedtogether.

The feedforward control operation of the active vibration suppressionapparatus according to this embodiment can be implemented by controllingthe rotational vibration suppression unit 60 on the basis of the signalobtained by the feedforward compensation computation section 5 c in thismanner. This makes it possible to effectively reduce/suppress rotationalvibrations in the structure 6 by the operation of the X-Y stage 45.

Although feedback control operation and feedforward control operationhave been separately described, both feedback control operation andfeedforward control operation can be simultaneously performed by drivingthe rotational vibration suppression unit 60 on the basis of the signalobtained by adding the two compensation computation results. Obviously,control may be performed by only one of feedback control operation andfeedforward control operation.

As described in the third embodiment, the rotational vibrations of thestructure 6 can also be reduced/suppressed by using an active vibrationsuppression apparatus using a linear-acting vibration suppression unit.With the active vibration suppression apparatus using only onelinear-acting vibration suppression unit, however, since not only amoment in the rotational motion direction, but also a reaction force inthe translation direction are produced, a sufficient vibrationsuppressing effect may not be obtained depending on the position wherethe apparatus is applied. In some cases, two or more linear-actingvibration suppression units are required to reduce/suppress rotationalvibrations.

In contrast to this, according to the apparatus of this embodiment,since the rotational vibration suppression unit constituted by therotational actuator and flywheel is used as an apparatus for performingvibration suppressing operation in the rotational motion direction, anecessary reaction force, i.e., a necessary torque, can be obtained byusing the single vibration suppression unit. The mechanism forgenerating a reaction force against a rotational motion mode can be mademore compact, and hence, an excellent vibration suppressing effect canbe obtained even in a precision device with size and weight restrictionsbeing imposed on a space where such an apparatus is mounted.

The active vibration suppression apparatus according to this embodimentis an apparatus for reducing the rotational vibrations of a vibrationsuppression target. Obviously, this operation can improve the vibrationsuppressing effect by suppressing vibrations in the translationaldirection as well as rotational vibrations in cooperation with an activevibration suppression apparatus using a linear-acting vibrationsuppression unit like the one described in the third embodiment.

Fifth Embodiment

In the fifth embodiment of the present invention, an active vibrationsuppression apparatus is applied to the reduction of the vibrations of apedestal structure 91 (shown in FIG. 10), on which the overallsemiconductor exposure apparatus, is mounted.

The pedestal structure 91 is basically installed on an apparatus mountpedestal 100 without the mediacy of a vibration isolation support means,and hence, is directly influenced by the vibrations of the apparatusmount pedestal 100. In addition, since the pedestal structure 91 isinfluenced by its own structural resonance itself, a level adjustingmechanism interposed between the pedestal structure 91 and the apparatusmount pedestal 100 to level the apparatus, and the like, resonancevibrations are also produced in the pedestal structure 91.

The apparatus according to this embodiment has an active vibrationsuppression apparatus mounted on the pedestal structure 91 to reducevibrations of this type, thereby decreasing the amount of vibrationstransmitted from the apparatus mount pedestal 100 and pedestal structure91 to the semiconductor exposure apparatus body through the vibrationisolation apparatus 92.

FIG. 14 shows an example of the structure of the apparatus according tothis embodiment. Basically, in this embodiment, an active vibrationsuppression apparatus is applied to a semiconductor exposure apparatusof the same type as that shown in FIG. 10. The same reference numeralsas in FIG. 10 denote the same functions, and the like, in FIG. 14, and adescription thereof will be omitted.

In the apparatus according to this embodiment, the linear-actingvibration suppression unit 50 and vibration detection unit 3 describedin detail in the third embodiment are mounted on the pedestal structure91. This apparatus reduces/suppresses the vibrations of the pedestalstructure 91 by using a compensation computation section 4 forperforming compensation computation processing for a signalcorresponding to the vibrations of the pedestal structure 91, which aredetected by a vibration detection unit 3, a feedforward compensationcomputation section 5 for performing a compensation computation based onthe operation state of a stage apparatus, such as a wafer stage 94 orreticle stage 95, or a signal from a control section 46 b for the stageapparatus, and the like.

The operation of the apparatus according to this embodiment will bedescribed next.

The apparatus according to this embodiment also performs the controloperation of feeding back the signal obtained by compensating for asignal corresponding to the vibrations of the pedestal structure 91 as avibration suppression target to a linear-acting vibration suppressionunit 50 by using the vibration detection unit 3 or compensationcomputation section 4, the control operation of feeding forward theoperation state of a stage apparatus or information from the stagecontrol section 46 b as a control section for the stage apparatus to thelinear-acting vibration suppression unit 50 by using the feedforwardcompensation computation section 5, and the like.

Feedback control operation using the vibration detection unit 3,compensation computation section 4, and the like, will be describedfirst. The feedback control operation is performed to reduce/suppressthe vibrations of the pedestal structure 91 by detecting vibrationsproduced in the pedestal structure 91 using the vibration detection unit3, performing an appropriate compensation computation for the resultantdetection signal using the compensation computation section 4, anddriving the linear-acting vibration suppression unit 50 on the basis ofthe resultant signal.

The compensation computation section 4 performs each compensationcomputation corresponding to a purpose to reduce/suppress the vibrationsof the pedestal structure 91. When, for example, a damping property isprovided to the structural resonance of the pedestal structure 91, acompensation computation is performed to apply a control forcecorresponding to the vibration velocity of the pedestal structure 91.Since the specific contents of a compensation computation to beperformed in this case are the same as those in the third embodiment, adescription thereof will be omitted.

Sky-hook spring control can be effectively applied to the apparatusaccording to this embodiment aimed at reducing/suppressing thevibrations of the pedestal structure 91 so as to increase the rigiditywith respect to a spatial absolute stationary coordinate system byapplying a control force proportional to the absolute displacement ofthe vibrations of the pedestal structure 91 to it. When an accelerationsensor is used as the vibration detection unit 3 and an electromagneticmotor having a high response property is used as linear-acting actuator51 of the linear-acting vibration suppression unit 50, this control canbe implemented by making the compensation computation section 4 performa compensation computation mainly including a double integralcompensation computation for a signal corresponding to the vibrationacceleration of the pedestal structure 91, which is detected by thevibration detection unit 3. According to such sky-hook spring control,vibration components other than those having the structural resonancefrequency of the pedestal structure 91 can be reduced/suppressed.

Obviously, a compensation computation other than the above compensationcomputation, including nonlinear compensation, may be applied or usedtogether by appropriately combining and using various signals such as anacceleration signal and velocity signal associated with vibrations,thereby controlling the vibrations of the pedestal structure 91 to anappropriate state.

In the apparatus according to this embodiment, as well, the compensationcomputation section 4 can also extract a frequency component to becontrolled by performing appropriate filter processing for an outputsignal from the vibration detection unit 3 in addition to thecompensation computation processing described above, or can performprocessing such as providing rigidity to restore an inertial load 52 toa predetermined neutral position by using an active means.

The feedback control operation of the active vibration suppressionapparatus according to this embodiment is implemented by controlling thelinear-acting vibration suppression unit 50 on the basis of the signalobtained by the compensation computation section 4 that performs such acompensation computation.

Feedforward control operation using the feedforward compensationcomputation section 5 will be described next.

The feedforward compensation computation section 5 in this embodimentperforms appropriate computation processing to make the linear-actingvibration suppression unit 50 effectively reduce/suppress vibrationsproduced in the pedestal structure 91 on the basis of a signal from thestage control section 46 b or a signal associated with the driven stateof a stage apparatus, such as the wafer stage 94 or reticle stage 95.The feedforward compensation computation section 5 performs compensationto generate a signal for canceling vibrations produced in the pedestalstructure 91 by the operation of a stage apparatus in consideration ofthe dynamic characteristics between the drive reaction force for thestage apparatus and vibrations produced in the pedestal structure 91when the drive reaction force is transmitted through the vibrationisolation apparatus 92, the mechanical rigidity between the stageapparatus and the pedestal structure 91, and the like. Obviously, thiscompensation computation is not limited to a linear compensationcomputation, and a nonlinear computation can be applied as thecompensation computation or used together.

The feedforward control operation of the active vibration suppressionapparatus according to this embodiment is implemented by controlling thelinear-acting vibration suppression unit 50 on the basis of the signalobtained by the feedforward compensation computation section 5 in thismanner.

Although feedback control operation and feedforward control operationhave been separately described, both feedback control operation andfeedforward control operation can be simultaneously performed by drivingthe linear-acting vibration suppression unit 50 on the basis of thesignal obtained by adding the two compensation computation results.Obviously, control may be performed by only one of the feedback controloperation and feedforward control operation.

In the apparatus according to this embodiment, since the vibrations ofthe pedestal structure 91 are reduced by the active vibrationsuppression apparatus, the amount of vibrations transmitted from theapparatus mount pedestal 100 or pedestal structure 91 to the apparatusbody through the vibration isolation apparatus 92 is suppressed to below. As a consequence, this operation can contribute to thereduction/suppression of vibrations produced in the semiconductorexposure apparatus body.

As a method of reducing the amount of vibrations transmitted from theapparatus mount pedestal 100 or pedestal structure 91 to the apparatusbody, a method of detecting the vibrations of the apparatus mountpedestal 100 or pedestal structure 91 by using a sensor, when an activevibration suppression apparatus is used as the vibration isolationapparatus 92, and controlling the active vibration suppression apparatuson the basis of the resultant compensation signal has beenproposed/developed. This control arrangement corresponds to a form offeedforward control. In this case, a signal to be fed forward is adetection signal representing the vibrations of the apparatus mountpedestal, which is generated by a mechanism including manyuncertainties. For this reason, control operation may become uncertain.This is a weak point in terms of the reliability of control operation.In feedforward control, any inappropriate signal to be fed forwardsimply becomes a disturbance.

The method described in this embodiment can obtain the same controleffect as this type of feedforward control because the vibrations of thestructure on the apparatus mount pedestal side are reduced. In addition,since control system operation is performed by feedback control on thevibrations of the pedestal structure 91 or feedforward control based onan operation signal from a stage apparatus that performs definiteoperation, uncertainties in the control operation are few as comparedwith feedforward control on the vibrations of the apparatus mountpedestal. Therefore, a desired vibration reducing/suppressing effect canbe obtained and more reliable operation can be achieved.

<Embodiment of a Semiconductor Production System>

A production system for a semiconductor device (e.g., a semiconductorchip, such as an IC or LSI, a liquid crystal panel, a CCD, a thin-filmmagnetic head, micromachine, or the like) will be exemplified. A troubleremedy or periodic maintenance of a manufacturing apparatus installed ina semiconductor manufacturing factory, or maintenance service such assoftware distribution is performed by using a computer network outsidethe manufacturing factory.

FIG. 19 shows the overall system cut out at a given angle. In FIG. 19,reference numeral 101 denotes a business office of a vendor (apparatussupply manufacturer), which provides a semiconductor devicemanufacturing apparatus. Assumed examples of the manufacturing apparatusare semiconductor manufacturing apparatuses for performing variousprocesses used in a semiconductor manufacturing factory, such aspre-process apparatuses (e.g., lithography apparatus, including anexposure apparatus, a resist processing apparatus, or etching apparatus,an annealing apparatus, a film formation apparatus, a planarizationapparatus, and the like) and post-process apparatuses (e.g., an assemblyapparatus, an inspection apparatus, and the like). The business office101 comprises a host management system 108 for providing a maintenancedatabase for the manufacturing apparatus, a plurality of operationterminal computers 110, and a LAN (Local Area Network) 109, whichconnects the host management system 108 and computers 110 to build anintranet. The host management system 108 has a gateway for connectingthe LAN 109 to Internet 105 as an external network of the businessoffice, and a security function for limiting external accesses.

Reference numerals 102 to 104 denote manufacturing factories of thesemiconductor manufacturer as users of manufacturing apparatuses. Themanufacturing factories 102 to 104 may belong to different manufacturersor the same manufacturer (e.g., a pre-process factory, a post-processfactory, and the like). Each of the factories 102 to 104 is equippedwith a plurality of manufacturing apparatuses 106, a LAN (Local AreaNetwork) 111, which connects these apparatuses 106 to construct anintranet, and a host management system 107 serving as a monitoringapparatus for monitoring the operation status of each manufacturingapparatus 106. The host management system 107 in each of the factories102 to 104 has a gateway for connecting the LAN 111 in the factory tothe Internet 105 as an external network of the factory. Each factory canaccess the host management system 108 of the vendor 101 from the LAN 111via the Internet 105. The security function of the host managementsystem 108 authorizes access to only a limited group of users. Morespecifically, the factory notifies the vendor via the Internet 105 ofstatus information (e.g., the symptom of a manufacturing apparatus introuble) representing the operation status of each manufacturingapparatus 106, and receives response information (e.g., informationdesignating a remedy against the trouble, or remedy software or data)corresponding to the notification, or maintenance information such asthe latest software or help information. Data communication between thefactories 102 to 104 and the vendor 101 and data communication via theLAN 111 in each factory adopt a communication protocol (TCP/IP)generally used in the Internet. Instead of using the Internet as anexternal network of the factory, a dedicated network (e.g., an ISDN)having high security which inhibits access of a third party, can beadopted. Also, the user may construct a database in addition to the oneprovided by the vendor and set the database on an external network, andthe host management system may authorize access to the database from aplurality of user factories.

FIG. 20 is a view showing the concept of the overall system of thisembodiment that is viewed at a different angle from FIG. 19. In theabove example, a plurality of user factories having manufacturingapparatuses and the management system of the manufacturing apparatusvendor are connected via an external network, and production managementof each factory or information of at least one manufacturing apparatusis communicated via the external network. In the example of FIG. 20, afactory having manufacturing apparatuses of a plurality of vendors andthe management systems of the vendors for these manufacturingapparatuses are connected via the external network of the factory, andmaintenance information of each manufacturing apparatus is communicated.In FIG. 20, reference numeral 201 denotes a manufacturing factory of amanufacturing apparatus user (semiconductor device manufacturer) wheremanufacturing apparatuses for performing various processes, e.g., anexposure apparatus 202, a resist processing apparatus 203, and a filmformation apparatus 204 are installed in the manufacturing line of thefactory. FIG. 20 shows only one manufacturing factory 201, but aplurality of factories are networked in practice. The respectiveapparatuses in the factory are connected to a LAN 206 to build anintranet, and a host management system 205 manages the operation of themanufacturing line.

The business offices of vendors (apparatus supply manufacturers), suchas an exposure apparatus manufacturer 210, a resist processing apparatusmanufacturer 220, and a film formation apparatus manufacturer 230,comprise host management systems 211, 221, and 231 for executing remotemaintenance for the supplied apparatuses. Each host management systemhas a maintenance database and a gateway for an external network, asdescribed above. The host management system 205 for managing theapparatuses in the manufacturing factory of the user, and the managementsystems 211, 221, and 231 of the vendors for the respective apparatusesare connected via the Internet or dedicated network serving as anexternal network 200. If trouble occurs in any one of a series ofmanufacturing apparatuses along the manufacturing line in this system,the operation of the manufacturing line stops. This trouble can bequickly solved by remote maintenance from the vendor of the apparatus introuble via the Internet 200. This can minimize the stoppage of themanufacturing line.

Each manufacturing apparatus in the semiconductor manufacturing factorycomprises a display, a network interface, and a computer for executingnetwork access software and apparatus operating software, which arestored in a storage device. The storage device is a built-in memory, ahard disk, or a network file server. The network access softwareincludes a dedicated or general-purpose web browser, and provides a userinterface having a window as shown in FIG. 21 on the display. Whilereferring to this window, the operator who manages manufacturingapparatuses in each factory inputs, in input items on the windows,pieces of information such as the type of manufacturing apparatus 401,serial number 402, name of trouble 403, occurrence date 404, degree ofurgency 405, symptom 406, remedy 407, and progress 408. The pieces ofinput information are transmitted to the maintenance database via theInternet, and appropriate maintenance information is sent back from themaintenance database and displayed on the display. The user interfaceprovided by the web browser realizes hyperlink functions 410 to 412, asshown in FIG. 21. This allows the operator in the factory to accessdetailed information of each item, receive the latest-version softwareto be used for a manufacturing apparatus from a software libraryprovided by a vendor, and receive an operation guide (help information)as a reference for the operator. Maintenance information provided by themaintenance database also includes information concerning the stepdriving profile of the projection exposure apparatus according to thepresent invention described above. The software library also providesthe latest software for setting the step driving profile.

A semiconductor device manufacturing process using the above-describedproduction system will be explained. FIG. 22 shows the flow of the wholemanufacturing process of the semiconductor device. In step 1 (circuitdesign), a semiconductor device circuit is designed. In step 2 (maskformation), a mask having the designed circuit pattern is formed. Instep 3 (wafer manufacture), a wafer is manufactured by using a materialsuch as silicon. In step 4 (wafer process), called a pre-process, anactual circuit is formed on the wafer by lithography using the preparedmask and the wafer. Step 5 (assembly), called a post-process, is thestep of forming a semiconductor chip by using the wafer manufactured instep 4, and includes an assembly process (dicing and bonding) and apackaging process (chip encapsulation). In step 6 (inspection),inspections such as the operation confirmation test and durability testof the semiconductor device manufactured in step 5, are conducted. Afterthese steps, the semiconductor device is completed and shipped (step 7).For example, the pre-process and post-process are performed in separate,dedicated factories, and maintenance is done for each of the factoriesby the above-described remote maintenance system. Information forproduction management and apparatus maintenance is communicated betweenthe pre-process factory and the post-process factory via the Internet ordedicated network.

FIG. 23 shows the detailed flow of the wafer process. In step 11(oxidation), the wafer surface is oxidized. In step 12 (CVD), aninsulating film is formed on the wafer surface. In step 13 (electrodeformation), an electrode is formed on the wafer by vapor deposition. Instep 14 (ion implantation), ions are implanted in the wafer. In step 15(resist processing), a photosensitive agent is applied to the wafer. Instep 16 (exposure), the exposure apparatus of the present inventiondescribed above exposes the wafer to the circuit pattern of a mask. Instep 17 (developing), the exposed wafer is developed. In step 18(etching), the resist is etched except for the developed resist image.In step 19 (resist removal), an unnecessary resist after etching isremoved. These steps are repeated to form multiple circuit patterns onthe wafer. A manufacturing apparatus used in each step undergoesmaintenance by the remote maintenance system, which prevents trouble inadvance. Even if trouble occurs, the manufacturing apparatus can bequickly recovered. The productivity of the semiconductor device can beincreased in comparison with the prior art.

As has been described above, the active vibration suppression apparatusaccording to the present invention reduces/suppresses the vibrations ofa vibration suppression target by using a vibration suppression unitusing a reaction force generated when an inertial load is driven as acontrol force. That is, since the vibrations of the vibrationsuppression target are reduced without generating any unnecessary forceoutside the apparatus, no vibrations are produced in the apparatus mountpedestal or a peripheral environment by the reaction force of a forcefor reducing/suppressing vibrations. In addition, this apparatus isconfigured to obtain a force acting on a vibration suppression target bythe drive reaction force of an inertial load in the control unit insteadof generating it between external equipment and the vibrationsuppression target. If, therefore, a vibration suppression apparatus canbe manufactured into an appropriate shape, a vibration reducing effectcan be obtained by installing the vibration suppression apparatus in aplace where a dashpot that has been used to reduce the structuralresonance of equipment or a reinforcing member for ensuring rigiditycannot be mounted.

In addition, the active vibration suppression apparatus according to thepresent invention compensates for a detection signal representing thevibrations of a vibration suppression target, the operation state ofequipment having a driving means, such as an X-Y stage, which may becomea vibration source of the vibration suppression target, or a signal froma control section for the equipment by computation processing, includinga nonlinear computation, and drives the vibration suppression unit onthe basis of the resultant signal, thereby reducing/suppressing thevibrations of the vibration suppression target. Therefore, highvibration suppression performance can be ensured by a relatively highcontrol gain with respect to vibrations that can be handled by a controlforce with which the operation of an inertial load in the vibrationsuppression unit falls within the allowable stroke range with asufficient margin. If large vibrations are produced that make theinertial load undergo a stroke over, control operation, e.g., ensuringstable operation by suppressing a control signal to prevent the strokeover of the inertial load, can be performed. That is, even if severerestrictions are imposed on the movable stroke of an inertial load mass,and the like, both a vibration suppressing effect and stable operationupon inputting of large vibrations can be realized. Therefore, themaximum vibration suppression performance under the restrictions can beobtained.

The semiconductor exposure apparatus according to the present inventionincludes the active vibration suppression apparatus forreducing/suppressing the vibrations of a vibration suppression target byusing the control unit which uses a reaction force generated when aninertial load is driven as a control force. With this arrangement,various types of structural vibrations can be reduced/suppressed, whichcannot be handled by a conventional vibration isolation apparatus, basedon the vibration isolation leg scheme. As a consequence, excellentexposure performance can be realized.

According to another aspect of the apparatus of the present invention,the vibrations of a pedestal structure serving as a pedestal when anexposure apparatus is installed on an apparatus mount pedestal arereduced/suppressed by using an active vibration suppression apparatus.This operation is equivalent to the reduction of the vibrations of theapparatus mount pedestal themselves. This makes it possible toreduce/suppress the amount of vibrations transmitted from the apparatusmount pedestal to the exposure apparatus through the vibration isolationapparatus, thus contributing to an improvement in the exposureperformance of the apparatus. This apparatus and method take feedbackcontrol or feedforward control based on an operation signal from a stageapparatus that performs definite operation instead of feedforwardcontrol based on a signal generated by a mechanism with manyuncertainties, such as feedforward control on the vibrations of theapparatus mount pedestal, which is implemented by using the conventionalactive vibration isolation apparatus. Therefore, this apparatus andmethod can realize vibration suppressing operation with highreliability.

As many widely different embodiments of the present invention can bemade without departing from the spirit and scope thereof, it is to beunderstood that the invention is not limited to the specific embodimentsthereof, except as defined in the claims.

1. An active vibration suppression apparatus comprising: an actuatorfixed to a vibration suppression target; an inertial load drivenrelative to the target by said actuator; and a driving system whichdrives said actuator based on a first signal corresponding to vibration,generated or to be generated, of the target, wherein said driving systemcomprises a compensation unit which performs a compensation for thefirst signal, wherein the compensation comprises: (i) a linearcompensation for the first signal to obtain a first compensated signal,and (ii) a nonlinear compensation for the first compensated signal toobtain a second compensated signal, a rate of a change in the secondcompensated signal to a change in an absolute value of the firstcompensated signal becoming less with an increase of the absolute value.2. An apparatus according to claim 1, wherein said actuator drives theinertial load in a straight direction.
 3. An apparatus according toclaim 1, further comprising a vibration detection unit which detects avibration of the target and outputs a detected signal as the firstsignal.
 4. An apparatus according to claim 1, wherein said compensationunit performs the compensation using a sigmoid function.
 5. An apparatusaccording to claim 1, wherein said driving system uses, as the firstsignal, one of a driving signal for a stage which is supported by thetarget and moves relative to the target, and a signal concerning adriving state of the stage.
 6. An apparatus according to claim 1,wherein the linear compensation comprises at least one of a proportionalcompensation, an integral compensation, a differential compensation, aphase-lead compensation, and a phase-lag compensation.
 7. An apparatusaccording to claim 1, wherein said compensation unit performs thenonlinear compensation using one of a monotone increasing function and amonotone decreasing function.
 8. An apparatus according to claim 1,wherein the compensation comprises the linear compensation and thenonlinear compensation as a composite compensation.
 9. A method appliedto an active vibration suppression apparatus, the apparatus comprisingan actuator fixed to a vibration suppression target, and an inertialload driven relative to the target by the actuator, said methodcomprising: performing a compensation for a first signal correspondingto vibration, generated or to be generated, of the target, wherein thecompensation comprises: (i) a linear compensation for the first signalto obtain a first compensated signal; and (ii) a nonlinear compensationfor the first compensated signal to obtain a second compensated signal,a rate of a change in the second compensated signal to a change in anabsolute value of the first compensated signal becoming less with anincrease of the absolute value; and driving the actuator based on thesecond compensated signal obtained in said performing step.
 10. A methodaccording to claim 9, wherein the compensation comprises the linearcompensation and the nonlinear compensation as a composite compensation.